The full cost to the taxpayer of the new Surbiton Health Centre is being withheld to prevent commercial competitors getting an upper hand on the NHS.

The project, which includes the health centre and Lime Tree Primary School, cost £15m to build.

It was paid for by a third-party investor, as part of a LIFT scheme, similar to a private finance scheme (PFI).

The NHS is leasing the land back in a 30-year contract but the amounts and arrangements of the total amount to be paid back have been withheld from the public.

A public version of the business case, approved by NHS Kingston in June 2010, said the revenue consequences of the new healthcare facility were within its “affordability envelope”.

Edward Davey, Kingston and Surbiton MP, said: “The overall sum we pay back is likely to be more than £15m, but that is what you expect.

“You can ask that about almost anything in the Government.

"When you buy a house and get a mortgage you end up after 25 years paying more than the ticket.”

Kingston Hospital will have to pay £66m by 2037 for its £33m PFI surgical centre, excluding the £266m for cleaning, catering, portering and security as part of the deal.