Career
He also had spells at Watford, Oxford United, Brentford and Mansfield Town. Southampton
Lawrie McMenemy signed Cassells for the Saints from Oxford United in March 1982, at the same time as Mark Wright. He scored his first goals for the club with two in a 5–5 thriller against Coventry City at the Dell on 4 May 1982.
He was never able to establish himself as a first-team regular and moved on to Brentford in February 1983.
Brentford and Mansfield
Whilst playing for Brentford it was rumoured that Keith once hit the floodlights with a shot at goal. On retiring from football, he became a police officer
