Apparently, at the recent agents meeting it was announced that in Reading East we may have an SDP candidate and an independent. We had an independent at the last general election in Reading East, but no SDP. The Liberal Democrat vote would seem the most in danger from an SDP candidate. But as no one knows who the candidate is at this stage I don't think they have that much to worry about as the mystery candidate won't have very much time to build a profile.
If my memory serves me correctly, the Tory candidate Rob Wilson stood for the SDP in the past.