The admission by the man who, as Lord Chancellor, helped make the case for the war for the Blair government in the Lords in 2003, comes amid increasing concerns that the Iraq inquiry chaired by Sir John Chilcot may not report until next year despite being launched six years ago.

Speaking in a BBC documentary about the fall of Labour in Scotland, Charles Falconer, who was born in Edinburgh and went to the prestigious Glen-almond College in Perthshire, pinned much of the blame on the “perception” of the Iraq war that many now believe was illegal.

He said: “We didn’t find weapons of mass destruction there and that was the basis by which we went in.

“So on that basis, we weren’t right to go in.”

Mr Blair’s former flatmate, when the two were starting out as barristers in the 1970s, admitted that the ex-Prime Minister also believes that.