An internal Labour memo, leaked to The Independent, reveals that Downing Street also toned down interviews with ordinary members who reflected the criticism inside the party of Tony Blair's "control freakery".
The party political broadcast, to be shown on Tuesday, was made by the Ginger Television company run by the media mogul Chris Evans, who is a Labour supporter. Its brief was to boost party membership - which fell from 405,000 to 388,000 last year - through vox-pop interviews in which people explain why they joined Labour.
However, some of their comments were too unpalatable for the three Blair aides who viewed the broadcast - Mr Campbell; Sally Morgan, Mr Blair's political secretary; and Anji Hunter, his special assistant. According to the memo from Steve Bates, Labour's broadcasting officer, they ordered the removal of an interview with a Scottish woman who said "I joined the Labour Party because I'm a socialist"; an Asian woman who said "the decisions are made at the top"; and a black woman who said "the leadership is only there at our behest". They also called for comments by Mr Blair on devolution, Northern Ireland and Europe to be edited out.
Last night, one Labour MP criticised No 10's "red-pen treatment" of relatively mild comments. "The control freaks have edited out the criticism of control freakery," he said, adding that the banning of the "S-word" (socialism) showed Mr Blair wanted to turn Labour into the "SDP mark two".
Mr Blair has said he regards the phrases "social democracy" and "democratic socialist" as interchangeable. The new Clause 4 of the party constitution, introduced by Mr Blair in 1995, said Labour was a "democratic socialist" party.
Labour sources denied the cuts had been made on political grounds. A spokesman said: "The Labour Party always shoots more film than we use in any party political broadcast. This was one of many memos on suggested edits."Reuse content