The Prime Minister should now consult Parliament over rules governing the conduct of ministers, Mr Brown said. He also called for the 1990 guidelines on financing ministers' defamation cases to include new measures to ensure that the use of taxpayers' money is revealed in Government accounts.
The twin call follows Monday's decision by Sir John Bourn, the Comptroller and Auditor General, to inquire into the Treasury's payment - under the then secret 1990 guidelines - of pounds 4,700 of charges incurred with the libel lawyers Peter Carter-Ruck and Partners when revelations about the Chancellor's unwelcome tenant, Sara Dale, surfaced in the News of the World. Sir John, head of the National Audit Office, started his examination yesterday.
In a letter to the Chancellor yesterday, Mr Brown said: 'It is now clear that the National Audit Office was never informed of the special nature of this expenditure and did not have a chance to examine it.
'Now that this examination is taking place, I hope you will agree with me that new reporting arrangements are necessary.'
Labour repeated the charge that using public money to pay the pounds 4,700 bill broke the 1990 Treasury Solicitor's rules on 'Defamation of Ministers and Civil Servants', because legal work in relation to unwanted publicity about Ms Dale did not relate to the Chancellor in his official capacity.
The Treasury has insisted throughout that the payment was justified because it was connected with the Chancellor's public role.
Mr Lamont has admitted privately to Mr Brown's office that he did not consult the Law Officers until after he had instructed the high-charging law firm to warn off newspapers from publishing defamatory material when he discovered the tenant renting his basement was carrying on a sex therapy business.
Pressing in the letter for a copy of any advice the Law Officers eventually gave, Mr Brown cites Paragraph 25 of Questions of Procedure for Ministers. This says: 'Ministers occasionally become engaged in proceedings primarily in their personal capacities but in circumstances which also involve their official responsibilities.
'In such cases they should consult the Law Officers before consulting their own solicitors, in order to allow the Law Officers to express a view on the handling of the case so far as the public interest is concerned or . . . to take charge of the proceedings . . .'