The SDP was formed in 1981 by the notorious gang of four Labour M.Ps. Roy Jenkins. Shirley Williams. Bill Rogers & David Owen. All were concerned about the shift of the Labour Party to the extreme left of the political spectrum. Much of the history is recorded on Wikipedia. Although, not totally correct - amendments have been sent but not yet recorded.
Twenty three Labour M.Ps. and one Conservative joined the new party. The leadership courted the Liberal Party and the two parties campaigned as the SDP/Liberal Alliance, some members eventually joining with the Liberals to form a new party. Remaining members continued with new members joining all the time, right up to today’s SDP.
If you agree with our ten SDP Principles, our party is the party for you.