I refer the hon. Member to the report published by the Department for Environment Food and Rural Affairs (DEFRA) on 8 November 2007 that gives the proportion of UK produce supplied to Government Departments, NHS and HM Prison Service.
Copies of the report are available on the DEFRA website at:
http://www.defra.gov.uk/farm/policy/sustain/procurement/index.htm
and have been deposited in the House of Commons library.