Mallett was coach at Blues from July 1964 and was given the managers job after the resignation of Gill Merrick in May 1965, a post he held for seven months before the appointment of Stan Cullis in December of the same year.
During his short spell as manager, however, he signed Trevor Hockey, Ron Wylie and Jim Herriot for Blues.
Mallett served as assistant manager to Cullis until both were dismissed in March 1970.
On leaving the Blues he went to to Panionios in Greece where he enjoyed 5 successful years before going to coach at New York Cosmos in the USA.