He later studied at the Slade School of Art, part of the University of London from 1957 to 1961, where he won the Tonks Prize for Life Drawing and the Steer Medal for Landscape Painting.

In 1985, Creffield was commissioned by the Arts Council to draw every cathedral in England, a task undertaken by living in a camper van for two years.

In 2005, Flowers Gallery, London, staged a major retrospective exhibition and published a catalogue including a foreword by novelist Howard Jacobson and a conversation between Dennis & Professor Lynda Morris.

[6] Creffield's importance as a contemporary draughtsman was also recognised in 2008 when he was included in the exhibition 'Drawn from the Collection, 400 Years of British Drawing' at Tate Britain.

In 2011 he staged a major exhibition entitled ‘Jerusalem’ at James Hyman Gallery, inspired by the city and by William Blake's great poem.