1 Introduction, scope and approach
Layer three of the Assessment of Risk (AoR) is an assessment of rare, extraordinary or, “reasonable worst-case,” scenarios which may not occur with sufficient frequency to appear in LFB incident data or are yet to have occurred. These scenarios are plausible reasonable-worst- case scenarios rather than predictions of events that are likely to come to pass.
Reasonable worst-case scenario (RWCS) risks are assessed against a range of impacts e.g. human welfare, behavioural impact, economic, infrastructure, environmental and security. These risks are taken directly from the London Risk Assessment (LRA), formally London Risk Register, produced by the London Resilience Forum (LRF). The risks for which LFB is the lead are scored using input from LFB subject matter experts but also include input from partners. Risks on which other partners lead are scored in a similar way. This gives the Brigade and the London Resilience Forum a shared partner-wide perspective on risks. This register includes risks that LFB will not have to respond to but may be affected by and for which it may need continuity plans.
Also included but presented independently of the LRA are highlighted risks that do not appear as separate items in the LRA (although they may be aggregated into a wider category) or in recent incident data, but are highlighted through cross departmental engagement. Risks from this section may progress to the LRA as separate items through the London Resilience Forum. Input from Operational Policy and Assurance Department is a key component in identifying risks for inclusion here through Operational, National, Joint and International Learning.
2 Objectives
The purpose of Layer three is to allow the Brigade to:
- plan and prepare for response to low frequency but high impact events.
- plan for combinations of events leading to a high overall demand on LFB resources.
- develop an evidence base for prioritised testing and exercising.
- communicate effectively with stakeholders regarding resourcing for low frequency high impact events
3 Limitations
The events and scenarios in this assessment are informed by the National Security Risk Assessment and partnership planning within the London Resilience Forum as well as cross departmental engagement within LFB. However, there is inherent uncertainty associated with assessing low-likelihood, high-impact events.
This assessment does not yet include assessment of cascading risks. There is work within the wider resilience forum regarding cascading risks.
4 Key Findings
Increasingly complex malicious threat picture
- Malicious acts. The number of malicious act threats recorded on the London Risk Register increased notably in 2024. A further increase in likelihood and severity of individual malicious threats occurred in 2025. The five risks which have increased from the 2025 assessment to the 2026 assessment all relate to malicious acts. This prevalence of malicious threats on the 2026 London Risk Assessment (LRA), previously London Risk Register, reflects the current partnership assessment of threat level across a spectrum of attack methodologies. LFB will be required to respond directly to incidents involving malicious acts where its capabilities are required or where statutory duties exist.
Critical service disruption
- Business continuity challenges. Items on LRA such as R89 High Altitude Electromagnetic Pulse, R50a National Electricity Transmission Failure and R21 Attack on UK electricity Infrastructure are likely to pose business continuity challenges for LFB through critical service disruptions as well as potentially triggering concurrent need for response services.
LFB-lead, High-Risks on LRA
- Fires in purpose-built high-rise flats. Fires in purpose-built high-rise flats remain a high risk, reduced from very high, with a reasonable-worst-case scenario scale incident assessed as having between 5% and 25% likelihood of occurring in any 12-month period. On 1st March 2026 there were 949 buildings in London known to LFB over 18 meters high, (high-rise buildings) that had a simultaneous evacuation strategy. These buildings are likely to perform in such a way during a fire that a stay put strategy is untenable.
- Major fire in care homes and hospitals. Fires in care homes and hospitals remain a high risk, unchanged from 2025, with a reasonable-worst-case scenario scale incident assessed as having between 1% and 5% likelihood of occurring in any 12-month period.
- Accident involving high consequence dangerous goods. Accident involving high consequence dangerous goods remain a high risk, unchanged from 2025 with a reasonable-worst-case scenario scale incident assessed as having between 1% and 5% likelihood of occurring in any 12-month period.
- Civil Nuclear Accident. This risk remains unlikely with a less than 0.2% chance of occurring each year. However, due to high consequence this remains a high risk on the assessment.
Climate Related
- Flooding. Two separate red risks and one amber risk relating to different types of flooding are recorded in the London Risk Assessment. Although LFB does not hold the statutory duty for flooding, these risks, if actualised, are likely to impose a significant operational demand on LFB as a category one responder with a duty for rescue.
- High Temperatures and Heatwaves. Periods of extreme heat remain a very-high risk on the London Risk Assessment. The assessment also includes acute risks such as wildfire that are linked to temperature and climate.
Highlighted Risks
- Heritage Fires. Heritage fires are not assessed separately in the London Resilience Forum’s LRA, falling within the broader category of R54b Fires in major entertainment and/or public building”, assessed as a medium risk. However, they are noted separately in this assessment due to the number and prominence of London’s approximately 40,000 listed buildings, buildings of special interest and four UNESCO World Heritage Sites - Westminster Abbey, Palace of Westminster, Royal Botanic Gardens Kew, Maritime Greenwich and the Tower of London.
Although the risks on this register are presented as reasonable-worst-case scenarios (RWCS), they are plausible in any given year. This is a distinction from Layer four of the AoR, where the intent is to look further ahead at risks becoming more concerning in the future. However, in 2026 – 2030 there is significant overlap between these types of assessment. Many RWCS described in the LRA are assessed as becoming increasingly likely or severe in the near future in the Brigade’s horizon scan.
5 Extraordinary Risks – London Risk Register 2025 (with updates on public risks from LRR 2026)
Status: Red
R95 Nuclear attack by a state on the UK mainland or UK overseas interests.
R76 Drought.
R21b Attack on UK electricity infrastructure – Cyber
R12 Non-state nuclear attack – urban area
R21b Attack on UK electricity infrastructure – Cyber
R89 High-Electromagnetic Pulse (HEMP)
Impact score: 5 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 2 (likely frequency of incidents occurring within London)
R50a Failure of National Electricity Transmission System
R14 Biological attack unenclosed urban
Impact score: 5 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 3 (likely frequency of incidents occurring within London)
R78 Pandemic
Impact score: 5 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 4 (likely frequency of incidents occurring within London)
R73 High Temperatures and heatwaves
R75b Fluvial Flooding
R16a Chemical attack – unenclosed urban area
R16b Chemical attack – enclosed urban area
R21a Attack on UK electricity infrastructure – conventional
R22b Malicious attack on civil nuclear installations – Cyber
R07 Malicious Rail Network Attack
R23a Malicious attack on fuel supply infrastructure – Conventional
R23b Malicious attack on fuel supply infrastructure – Cyber
R75c Surface Water Flooding
Impact score: 4 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 3 (likely frequency of incidents occurring within London)
L54a Fires in purpose-built high-rise flats
R64 Food Supply Contamination
R79 Outbreak of an Emerging infectious disease
R71 Severe Space Weather
R74 Low temperatures and snow
R17 Chemical, Biological or Radiological attack on water supply infrastructure
R19 Conventional attack on chemical infrastructure
R40d Marauding terrorist attack - firearms
Impact score: 4 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 4 (likely frequency of incidents occurring within London)
R02 Conventional attack on government
R40b Land based terrorist attack - improvised explosive device
Impact score: 4 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 5 (likely frequency of incidents occurring within London)
Status: Amber
R52 Civil Nuclear Accident
R22a Malicious attack on civil nuclear installations – conventional
Impact score: 5 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 1 (likely frequency of incidents occurring within London)
R48 Loss of Positioning, Navigation and Timing (PNT) Services
L71a Large Aircraft incident in proximity to Airport
R08 Malicious Aviation Incident
R80a Major outbreak of foot and mouth disease
R51 Failure of Gas Supply Infrastructure
Impact score: 4 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 2 (likely frequency of incidents occurring within London)
R40 Rail Accident
R44 Accident involving high consequence dangerous goods
R46 Malicious Drone Incident
R49 Simultaneous loss of all fixed and mobile forms of communication
R80b Major Outbreak of Animal Disease – Avian Influenza
L19 Groundwater Flooding
R75a Coastal Flooding R77 Poor Air Quality
R20a Attack on UK gas infrastructure – conventional
L54e Major fire in care homes and hospitals area
R23a Malicious attack on fuel supply infrastructure – Conventional
R23b Malicious attack on fuel supply infrastructure - Cyber
Impact score: 3 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 3 (likely frequency of incidents occurring within London)
R67 Volcanic eruption
R72 Storms
R15 Radiological attack – unenclosed urban area
R09 Malicious Maritime Incident
R20b Attack on UK gas infrastructure – Cyber
R15 Radiological attack – unenclosed urban
Impact score: 3 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 4 (likely frequency of incidents occurring within London)
R55bTechnological failure at a UK critical financial market infrastructure
R82 Public Disorder
R84 Industrial action - firefighters
R87 Reception and Integration of British Nationals Arriving from Overseas
R24 Cyber-attack - health and social care system
R04a Person-borne improvised explosive device
R04c Marauding attack (low sophistication)
R05b Maritime Terrorist Attack – Marauding Terrorist Firearms attack on a passenger ferry
Impact score: 3 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 5 (likely frequency of incidents occurring within London)
Status: Yellow
R45Aviation Crash
R53 Radiation Release from overseas nuclear site
R56 Accidental Fire or explosion at an onshore major hazard (COMAH) site
R57 Accidental Large Toxic Chemical Release from a COMAH site.
R58 Accidental fire or explosion on an offshore oil or gas installation.
R59 Accidental fire or explosion at an onshore fuel pipeline.
R62 Reservoir/Dam Collapse.
L66 Radioactive incident caused by mishandling of radioactive material
Impact score: 4 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 1 (likely frequency of incidents occurring within London)
R63 Water Supply Infrastructure
HL22 Building Collapse
HL23 Bridge Collapse
Impact score: 3 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 1 (likely frequency of incidents occurring within London)
R47 Disruption of space-based services
R50b Regional Failure of the Electricity Network
R60 Accidental fire or explosion at an onshore major accident hazard pipeline
R65 Major Fire
HL105 Complex built environments
R10 Strategic hostage taking
Impact score: 3 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 2 (likely frequency of incidents occurring within London)
R54b Fires in major entertainment and/or public building
R10 Strategic hostage taking
R86 Industrial Action – fuel supply
Impact score: 2 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 2 (likely frequency of incidents occurring within London)
HL10 Local accident on motorways and major trunk roads
R37 Insolvency of Supplier of Critical Services to public sector
L71b Small aircraft incident in proximity to airport
R26 Cyber-attack - telecommunications systems
R83 Industrial Action – Public Transport
Impact score: 2 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 3 (likely frequency of incidents occurring within London)
R36 Major Social Care Provider Failure
R39 Failure of a supplier of CNI Chemicals
R55a Technological Failure at a Systemically Important Retail Bank
R66 Wildfires
R05a Maritime Terrorist Attack – Vehicle borne improvised explosive device (VBIED)
R13 Anthrax letters
R85 Industrial Action – Prison staff
Impact score: 2 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 4 (likely frequency of incidents occurring within London)
R11 Assassination of a high-profile public figure
L54c Fires involving landfill and waste processing sites
Impact score: 2 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 5 (likely frequency of incidents occurring within London)
Status: Green
R61 Accidental work-related (laboratory) release of a hazardous pathogen
R38 Insolvency affecting fuel supply.
Impact score: 2 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 1 (likely frequency of incidents occurring within London)
R54 Radiation exposure from transported, stolen or lost goods
R80d Major Outbreak of Animal Disease – African Swine Fever
R80c Major Outbreak of Animal Disease – African Horse Sickness
R68 Earthquake
Impact score: 1 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 1 (likely frequency of incidents occurring within London)
R42 Major Maritime Pollution Incident
R30 Malicious Attack – UK Financial CNI
Impact score: 1 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 2 (likely frequency of incidents occurring within London)
R41 Larger Passenger Vessel Accident
R32 Major interference in UK democratic process
HL21 Land Movement
R28 Cyber-attack – government critical systems loss
R29 Cyber-attack– government data breach
Impact score: 1 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 3 (likely frequency of incidents occurring within London)
R25 Cyber-attack – transport sector
Impact score: 1 (on a scale of 1-5 where 5 is the highest option)
Likelihood score: 4 (likely frequency of incidents occurring within London)
6 Highlighted Extraordinary Risks
These are foreseeable risks which are not identified in the last five years of LFB data as being very high or high and are not currently featured as separate items in the London Resilience Forum’s London Risk Assessment but are highlighted through cross departmental engagement and as such are considered appropriate to highlight separately as part of the LFB’s Assessment of Risk. Risks from this section may, if appropriate, progress to the LRA as separate items through partner engagement in the London Resilience Forum.
Risk
Fire in major heritage buildings (included in LRA wider category of, R54b Fires in major entertainment and/or public building”)
Outcome description
London has approximately 40,000 Historic listed buildings, buildings of special interest and modern buildings that store historic relics and artefacts. This includes four UNESCO World Heritage Sites - Westminster Abbey, Palace of Westminster, Royal Botanic Gardens Kew, Maritime Greenwich and the Tower of London. LFB responded to almost 7800 incidents in 2024 that involved or were within close proximity of Historic Listed Buildings.
Examples of recent significant incidents that have occurred in London or in other countries
- Cutty Sark Fire – 2007 – Large fire occurred on the Cutty Sark, almost destroying the historic ship.
- Glasgow School of Art, Glasgow – 2014 – Large fire at the Glasgow School of Art.
- Morden Mosque fire – 2015 – Large fire damaging 50% of ground floor of Europe’s largest mosque.
- The National Museum of Brazil was destroyed by a large fire in September 2018. Although some items were saved, it is believed that 92.5% of its archive of 20 million items were destroyed in the fire.
- Notre-Dame de Paris fire – 2019 – Major fire in a historical cathedral in Paris requiring over 400 firefighters to extinguish costing over €1 billion to restore.
- Somerset House fire, London – August 2024 - the fire damaged parts of the third floor and the roof of the west wing.
- Woolton Hall Fire, Liverpool - August 2025, Grade I-listed mansion suffered roof collapse and structural damaged after a fire.
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