David Cameron entered the fray with his opinion of Nicola Sturgeon on Friday. He was speaking following his keynote speech at the one-day Scottish Conservatives conference in Perth.
"I wouldn't have written that letter and I think she has got some serious questions to answer." he said.
"It is right though that members of parliament are called upon to take up cases sometimes with people that your profoundly disagree with and you have to do that.
"I remember taking up the case of someone who was imprisoned overseas - of course you have to take up these cases, but I think you have to be careful in what you say and how far you go.
"I think in advising that there should not be a custodial sentence that does seem to me to cross a line, so having read the letter that she sent I must say there are some parts of it where she has some very big questions to answer."
This matter is completely one for the Scottish Parliament and nothing whatsoever to do with Westminster politicians.
Mr Cameron also said in his speech that he would introduce a working relationship with the Scottish government. Officially commenting on Scottish Parliament affairs is not the way to gain friends and influence people - quite the opposite.
Don't make yourself more unpopular in Scotland Mr Cameron, stick to non-devolved issues. If you don't have policies that will benefit to Scotland, which I doubt, then I suggest you keep your thoughts to yourself and allow the Scottish Parliament to resolve the matter by their own methods.