Dinnis obtained his Football Association "A" Licence coaches badge and was then employed as
reserve team coach at
Blackburn Rovers from 1970 to 1975. Dinnis briefly acted as
caretaker manager of the club, when
Ken Furphy left to join
Sheffield United. He took charge of six matches with the first team, winning three and losing three. In 1976, Newcastle reached the
Football League Cup Final against
Manchester City, where they lost 2–1. When Lee suddenly resigned as manager in early 1977 after only 18 months in charge, the Newcastle board first offered the job to the
Bolton Wanderers manager,
Ian Greaves but he turned the job down.
Later years He coached
Philadelphia Fury of the
North American Soccer League in 1978, but resigned mid-season and was replaced by player-coach
Alan Ball. He was appointed assistant coach to the
Vancouver Whitecaps head coach
Tony Waiters, where they went on to win the
Soccer Bowl. Dinnis returned to Blackburn three years later, assisting
John Pickering. Afterwards, he joined
Bristol City as chief scout, and from January and April 1982, he was assistant manager to
Roy Hodgson. Following his departure from Bristol City, he gained a Diploma in Physical Education at
Carnegie College, Leeds. Dinnis returned to football, spending six months as a coach at
Middlesbrough, before a short spell as a youth coach at
Al-Ittihad who were then managed by
Bob Houghton. He later spent time coaching at
Accrington Stanley,
Barrow and for the centres of excellence at
Burnley and
Bolton Wanderers. He also worked as a summariser and analyst for
BBC Radio Lancashire up until the late 2000s, dealing with Blackburn,
Blackpool, Burnley and
Preston North End. Parallel to his coaching jobs, Dinnis was a physical education teacher, firstly at
Canon Slade School in
Bolton, and then at
Clitheroe Royal Grammar School. ==References==