The 1979 election marked an electoral turning point, as Margaret’s Thatcher’s Conservatives swept southern England. The Tory tide did not stop at the Tamar. In Cornwall only David Penhaligon was able to resist. Labour had already lost its sole Cornish seat at Falmouth and Camborne in 1970 and sank to a low of less than 10% of the vote in1983. After the shock of 1979 subsided, the Liberals, now Liberal Democrats, found themselves established as the clear alternative to the Tories, on around 40% of the vote.
(The Bodmin constituency was renamed South East Cornwall in 1983.)
Here are the detailed results by constituency.