Allan was born and educated in England, living in Surrey and Oxfordshire before moving to Boston and becoming a naturalized American citizen. In his youth he lived in Belgium, Italy (Sardinia), and Madagascar as well as England. He received a doctorate at Oxford University in literature with a focus on Joseph Conrad. After graduating he traveled to India, South Africa, Peru, Tunisia and all through Europe. He worked for a time with disturbed adolescents before teaching literature at Farleigh-Dickinson University in Wroxton, England. After moving to Boston he began teaching at Curry College where he is a full professor. He has also taught prisoners in Massachusetts jails and has a counseling practice.
His work with his father, Jim, an RAF prisoner of war during WW2, on a memoir, From Coastal Command To Captivity, led to an understanding of the ways memoir writing can heal trauma. Allan now teaches memoir at The Blues Hills Writing Institute at Curry College.
In his spare time he restores antique motorcycles. He lives outside Boston with his wife and has two adult step-children.