English Heritage has awarded a £330,000 grant to Bletchley Park for urgent repairs to the roof of the estate where codebreakers helped decrypt enemy messages during the second world war.

"The rooms of the mansion, embellished with decorative plasterwork, painted ceilings, timber panelling and fine fireplaces, are all at high risk of irreparable damage from water seeping through the roof," said a spokesman for English Heritage. The renovation work is set to be completed by March.

English Heritage is also in talks with the Bletchley Park Trust and Milton Keynes Borough Council to raise a further £600,000 towards the restoration of the on-site huts, which housed the scientists during the war and are "in desperate need of repair".

It will provide £100,000 a year for the next three years from April if match funding of £300,000 can be secured from the trust and council.

Vanessa McPake, cabinet member for heritage at Milton Keynes Borough Council, said: "The [governing] Liberal Democrat group has agreed to consult the public and our partners, as part of the 2009-10 budget process, regarding matching the English Heritage additional funding."