I didn't agree wit the release of al-Megrahi and I suspect there is a lot more to this than we shall ever learn, but this cannot go without comment.
Whether or not these politicians choose to go to America to help imrove the election prospects of a few senators is a matter for them. But the American Ambassador should be told sharply that the UK is a sovereign nation, not a part of the USA, and that the questioning by the US legislature of UK government ministers about decisions made in their own country is the sort of behaviour Britain wouldn't have got up to when it had an Empire.
Perhaps if we gave them a list of Americans suspected of being involved in torturing innocent people they would send then over to a Parliamentary Select Committee?
I don't think so.