Mostaque started his career in the private sector with Ernst & Young and the Royal Bank of Scotland before a long career in the civil service. During his time in Whitehall, he worked across several government departments, including the Home Office, HM Treasury, and the Cabinet Office.
Before joining the Brigade, Mostaque was the Managing Director of Finance, Portfolio & Performance for the House of Commons and previously served as Finance Director at the House of Lords. He also chairs the Governing Board of a primary school in Brent.
At the London Fire Brigade, he oversees Corporate Services, which encompasses Finance, General Counsel, Procurement and Commercial, Property and Technical Services, and ICT.