London — Britain's intelligence services, plagued by spy scandals in the last two decades, are about to undergo a new ''house cleaning'' as a result of the Franks Committee report on the Falklands war.
In an opening move, Prime Minister Margaret Thatcher has endorsed a key Franks recommendation: that chairmanship of the Joint Intelligence Committee (JIC), the central clearinghouse for inflowing intelligence, should become the full-time job of a Cabinet-level official.
At present chairmanship of the JIC is held part-time by the Foreign Office, which came in for sharp criticism from Franks and others unhappy about the link between intelligence gathering and political decisionmaking as it functioned during the crisis in the South Atlantic.
The Foreign Office is said to be fighting a solid rear-guard action to keep its man at the helm of the JIC, but Mrs. Thatcher is contemplating another solution. She may decide to appoint a senior retired official to this sensitive post.
Parallels are being suggested between this idea and Winston Churchill's decision during World War II to have his own security and intelligence coordinator in the Cabinet office.
Whatever choice the prime minister makes, it will be seen as a prelude to a thoroughgoing review of intelligence performance, with special reference to the way security information is passed on to ministers and acted upon.
Whitehall officials claim the intelligence machine is highly professional and staffed by fully qualified people. But there was a sluggishness in the way information on the developing Falklands crisis was passed through to ministers.
Thatcher wants the intelligence network to be more responsive to political requirements. She already has her own personal foreign-affairs advisers. If she puts in her ''own man'' as chairman of the JIC, it will represent a further buildup of prime ministerial power over foreign policy.
As reforms are prepared, the Foreign Office has been battling hard to limit the damage to its reputation. The former foreign secretary, Lord Carrington, who resigned over the Argentine invasion of the Falkland Islands, has defended the Foreign Office's role in the crisis.
The present foreign secretary, Francis Pym, said in House of Commons special debate on the Franks report that there was ''no evidence of collective neglect'' in the findings of the committee.
Thatcher has adopted a politically robust line as well, aware that her government's success in the Falklands campaign is a powerful electoral asset. She is, however, known to be unhappy about the weaknesses in intelligence gathering and assessment brought to light by the crisis.