Does one need to be an MP (elected) to become a Cabinet Minister?

A Civil Servant cannot be a Cabinet Member as it means the role of a Civil Servant is to advise a Cabinet Minister and then implement the decisions of the Cabinet, and Parliament as a whole. You do not need to be an elected MP to be in Cabinet, indeed the Leader of the House of Lords is an automatic Cabinet position (currently Lord Strathclyde).

It is becoming less acceptable for members of the House of Lords to be appointed to Cabinet as they are not able to answer questions in the elected House of Commons, and indeed prior to the 2010 General Election when Gordon Brown had two or three members of the Lords (Lord Mandelson at Business, Innovation and Skills and Lord Adonis at Transport) in his Cabinet the Speaker of the Commons and the Procedure Committee were looking at ways in which they could be made accountable to the House of Commons, but because David Cameron hasn't followed Gordon Brown's example in putting members of the Lords into his Cabinet, the issue has been put somewhat on the backburner.

Civil servants can't make political choices. But no you don't need to be an MP, lord carington being a good example.

In theory, you could have a non-elected cabinet. But the prim-minister must be a MP. So the government would still controlled by the electorate.

You don't have to be an MP to be in cabinet. You can be a member of the House of Lords, or a private citizen, but you can't be a civil servant (at least not at the same time ... you would have to resign).

Paddy Ashdown was a cabinet member of Blairs Government. Now that tells you a lot. Ashdown has to be the biggest waste of space in recent years.

Sturgeon in Cabinet