This report investigates the extent to which private consultancy (“Big Con”) is embedded in local public procurement in London. It does so in the context of academic literature – notably Mazzucato and Collington’s The Big Con (2023) – that suggests consultancy dependency weakens public administration and state capacity, with risks to institutional memory, accountability and long-term value for money.

Specifically, we compared transaction-level spending releases from London councils, to enable comparison between different local authorities over time. Findings were validated by manual checks against source CSVs and comparison with Freedom of Information responses and published reporting. The numbers in this report are  giving us a conservative estimate which should be read as a lower bound.

Key findings:

• Councils across London are highly dependent on consultancies.

• The average annual consultancy spending per council increased 76% between 2013 and 2023, from £11.5 million to £20.2 million.

• Across London local authorities in 2024, consultancy spending totalled £555 million.

• Nearly 30% of London councils have spent 5% or more of their annual budgets on consultancies at least once since 2010.

• Large outsourcing and managed-service firms take home the largest portion of council spending:

• From 2010 to 2024, London councils have paid:

• All councils show sustained reliance on external providers for delivery and contingent capability rather than short, tightly-scoped advisory work. This kind of work is more likely to impact autonomy, capability building and accountability in local government.