Former Bletchley Park codebreaker Baroness Trumpington, 90, also said that she thought that the SNP's push for independence was "absolutely crazy".
The peer became an internet sensation two years ago after footage emerged of her making the obscene signal towards her Conservative colleague Lord King. She has since insisted that he "got what he deserved" after he made a reference to her age during a debate in the Lords.
The former agriculture minister, who served under Margaret Thatcher, laid into Mr Salmond in an interview with the BBC's Daily Politics.
She said: "The Scots are really led by a mad man. I think it's absolutely crazy what they're trying to do. Well, I hope their leader goes down, down, down."
A spokesman for Mr Salmond declined to comment on her remarks last night.
Baroness Trumpington was made a life peer in 1980.