The comment was revealed by a top academic who had had access to senior Labour figures during the writing of a book on the 2105 General Election.
Philip Cowley, who teaches politics at London’s Queen Mary University, told an audience at the launch of the book that he had asked about Labour’s virtual wipeout north of the Border.
Prof Cowley, who co-authored ‘The British General Election of 2015’ along with Dennis Kavanagh, told students that an unnamed MP had spoken about Labour’s performance in Scotland.
Prof Cowley said: “There was an interview with a current, serving Shadow Cabinet member, who told us the result in Scotland had an upside.
“This was after the election, and we naively said ‘how could it possibly have an upside?’
“And he said, ‘well because it’s got rid of 40 f*****g useless MPs’.”
Referencing Labour’s analysis of the party’s performance in the election, Prof Crowley can be heard adding: “You won’t find that in Margaret Beckett’s report.”
Labour lost 40 seats in Scotland, with Ian Murray the only survivor as he held onto the Edinburgh South seat.
The SNP enjoyed a series of victories over Labour big-hitters, with the likes of Tom Greatrex, Margaret Curran, Gregg McClymont and Ian Davidson all losing their seats.
Former Shadow Foreign Secretary Douglas Alexander was defeated by Mhairi Black while former leader of the Scottish Labour Party Jim Murphy lost a 10,000 majority to Kirsten Oswald.
Recent polls have indicated Scottish Labour could be beaten into third place by the Scottish Conservatives at May’s Scottish Parliamentary Election.
• The comments can be heard from 9 minutes 32 seconds in