Gordon Brown, the shadow Chancellor, said yesterday: 'I have written to Mr Major asking him to agree that new rules be drawn up and to spell out his proposals.'
The Prime Minister's office said Mr Brown would receive a reply after Mr Major returned from the US today, although the code of conduct, Questions of Procedure for Ministers, was normally up- dated after a general election.
It was disclosed last month that Mr Lamont had received a secret Treasury contribution of pounds 4,700 to help meet legal bills following newspaper reports last year that he had unwittingly let his house to a sex therapist.
The remaining pounds 18,414 of his legal bills was met by anonymous Conservative Party supporters, and the Commons Select Committee on Members' Interests is considering a complaint that payment was not logged in the register of members' interests.
Sir Geoffrey Johnson-Smith, the committee's Conservative chairman, is drafting a response to that complaint. But even if it is decided that anonymous payments should in future be registered, Mr Lamont should escape censure.
Meanwhile, Dale Campbell- Savours, an Opposition agriculture spokesman, is threatening to make a complaint about John Gummer, Minister for Agriculture, over revelations that a meat company spent an estimated pounds 2,000 renovating a pond at Mr Gummer's Suffolk home for an agricultural exhibition. Mr Gummer has said that the exhibition left him out of pocket.