In his first match as a
trialist, at half time and 3–0 down he was told by then manager
Jack Charlton "you are the worst footballer I have ever seen in my life. You won't make a player while your arse still points to the ground". He was told to "hop it" therefore losing his room at the hotel for all the trialists. He stayed in a cleaned out coal shed behind the hotel. Refusing to give up, he trained alone in a car park near
Ayresome Park where he was spotted by then Boro captain
Graeme Souness. Middlesbrough, managed by John Neal now, signed Johnston in 1977 making his first team debut for Middlesbrough, aged 17, in a 3–2 FA Cup victory against
Everton. His league debut came on 4 February 1978 in a 2–1 victory over
Birmingham City at
St Andrew's and he scored his first goal later that season in a 2–1 home league defeat to
West Ham United. Johnston scored 16 goals in 64 league games for Middlesbrough before moving to
Liverpool in 1981 for
£650,000 Johnston made his Liverpool debut in August 1981, coming on as sub for
Ray Kennedy in the 1–0 league defeat to
Wolverhampton Wanderers at
Molineux. Johnston's first start came in the
Intercontinental Cup fixture against Brazilian side
Flamengo. Johnston scored his first goal for Liverpool on 8 December 1981 against
Arsenal at
Anfield, during a
League Cup fourth round replay. Johnston opened the scoring in the fifth minute of extra time in a 3–0 win. Johnston became a crowd favourite at Anfield during his long spell with the club.
Ian Rush secured the win with a late third. ==International career==