The Barnett Formula gives the Devolved Administrations in Scotland, Wales and Northern Ireland shares of changes in public expenditure allocations to UK Government Departments. It is a matter for individual UK Government Departments to allocate spending to individual regions of England such as London. Details of operation of the Barnett Formula are available in the Treasury publication ‘Funding the Scottish Parliament, National Assembly for Wales and Northern Ireland Assembly: Statement of Funding Policy’.
Full details of identifiable spending by region including London may be found in Chapter 9 of Public Expenditure Statistical Analyses 2007 (Cm 7091).