Richards was born in Nottingham, Nottinghamshire. He studied at Reading University. Between 1975 and 1980, he worked for the Berkshire Archaeological Unit, helping to build the county Sites and Monuments Record. He excavated and carried out a survey of the Berkshire Downs.
In 1980 he joined the new group Wessex Archaeology, based in Salisbury. He ran the Stonehenge Environs Project, a detailed study of Stonehenge and its surrounding landscape. This gave him his first experience of the media, where he contributed parts to programmes about Stonehenge.
With fellow project managers Peter Cox and John Hawkes from Wessex Archaeology, Richards started AC Archaeology in 1991. This was a small independent organisation, still based in Wiltshire, created when the founders decided they wanted an alternative to large organisations.
After three years Richards left the world of commercial archaeology and joined English Heritage to work on its Monuments Protection Programme (MPP). Returning to his roots in fieldwork, he inspected sites and prepared reports on the protection of important archaeological sites in Wiltshire, Hampshire and the Isle of Wight.
Shortly after joining the MPP, Richards was asked to contribute to a TV programme about the construction of Stonehenge. His ideas led eventually to the programme Meet the Ancestors.
Meet the Ancestors was commissioned in late 1996. In the spring of 1997 Richards took a year's leave from English Heritage to work on it. He resigned his day job to work full-time in broadcasting and writing when a second series was commissioned.
As of 2005 he has presented six series of Meet the Ancestors, a five-part series Blood of the Vikings in 2002, both for BBC 2. In addition, he has written books to accompany both series. For Radio 4 he has presented eleven series of Mapping the Town.
Richards is also responsible for creating two site-interactive games: Hunt the Ancestor (for which he won a British Archaeology award) and Viking Quest, for the BBC History website. He has also been a regular contributor to the BBC History website and magazine.
He also received a British Archaeological Award for the programme Chariot Queen. On his personal website he also notes receiving a Blue Peter badge.
In 2007 he published 'Stonehenge: The story so far' (English Heritage) (ISBN 978 1 905624 00 3). Other works include 'Stonehenge; a history in photographs' (English Heritage) (2004) and 'The amazing pop-up Stonehenge' (English Heritage) (2005).
Richards lives with his family in Shaftesbury, Dorset where he maintains his special interest in the prehistory of Wessex and particularly Stonehenge.
He is patron of the Friends of Cromford Canal.