David Johnston, son of Scottish international Bert Johnston who won the FA Cup with Sunderland in 1937, made ten appearances for Exeter City in the early-1960s after signing from Leicester City. He subsequently played for Stockport County. 

Previously with Bishop Auckland, David signed for Leicester City in February 1960 as an 18-year-old but, without making a first-team appearance, was given a free transfer at the end of the 1961/62 season.

Moving to Exeter City in May 1962 - as one of several younger players signed by manager Cyril Spiers - David made his debut in the right-back position in the opening day defeat against Torquay United. Remaining in the side for the following four games, he rarely featured there afterwards as Cec Smyth took his place in the starting line-up. Playing just five more league games - in a variety of positions - David was released to join Stockport County in July 1963 where he was to make 26 appearances in a single-season stay. 

He subsequently joined Tranmere Rovers but failed to make the first-team.