David Owen, the leader of the SDP who famously refused to go along with the merger with David Steel's Liberal party, became a huge opponent of the UK adopting the Euro, long before Gordon Brown in effect did the same, but still believed we were better 'in' than 'out'. Confession time - I helped out in the SDP's election campaign in Greenwich in the 1980s which Rosie Barnes, to everyone's surprise especially her own, she won! I had refused to help in the Lewisham East seat where I lived, having met Polly Toynbee, the party's candidate, and taken an instant dislike to her!
Rod Liddle, who may be their best known supporter now, was a confirmed Brexiteer who loved goading Remain supporters, but doesn't appear to mention the subject much nowadays.