Dean established his reputation as a member of the Keith Tippett Sextet from 1968 to 1970, and in the band Soft Machine from 1969 to 1972.

[6] From 1975 to 1978 he led a nine-piece band called Ninesense,[6] performing at the Bracknell Jazz Festival and similar events.

Following this, his own groups were usually quartets or quintets, and most often worked in the free jazz mode, with little or no pre-composed material, such as Soft Heap with Mark Hewins.

[7] However, he also continued to work with other groups that were very composition-based, such as guitarist Phil Miller's In Cahoots, drummer Pip Pyle's Equipe Out,[6] and various projects with former Soft Machine bassist Hugh Hopper.

[4] Featuring Dean, three albums of the Legacy have been released: Live in Zaandam (CD, rec.