He was a councillor on Slough Borough Council from 1965 and first stood for Parliament in 1966 for Birkenhead, failing to win the strongly Labour seat. He became Member of Parliament for Bristol North East after winning the seat by 462 votes in the 1970 election. However, significant boundary changes before the next election in 1974 saw Adley move on to become member of parliament for the new seat of Christchurch and Lymington. He would safely hold this seat from 1974 to 1983, and then after further boundary changes the Christchurch seat from 1983 until his death with one of the largest Conservative majorities in the country.