Notes from a Small Island by Bill Bryson — Bryson's affectionate and often funny journey around Britain includes stops in towns like Luton, and captures something of the texture of English urban life in the 1990s.
The Bedfordshire and Hertfordshire Regiment and related local histories — various volumes on Bedfordshire cover the county's history, industries, and communities in detail. The Luton Museum service has published pamphlets on lace-making history that are worth seeking out.
Twice Migrants: East African Sikh Settlers in Britain by Parminder Bhachu — a sociological study of South Asian communities in Britain relevant to understanding towns like Luton with large East African Asian populations.
Discovering the Chilterns and the Vale of Aylesbury — a useful guide to the broader region around Luton, covering walking routes, historic houses, and villages within easy reach.