In the late 1970s Fergusson became active in Conservative politics. As a firm opponent of devolution, he spoke at conferences trying to persuade the Conservatives to oppose the Scottish Assembly; after this campaign was successful, he was a member of the "Scotland Says No" campaign for the devolution referendum. At the 1979 elections to the European Parliament, Fergusson fought the Strathclyde West constituency, which had seemed safe for Labour; however, a collapse in the Labour vote saw him elected by 1,827 votes.