Malcolm came to Oxford in 1970 as the City’s first full-time local history librarian, taking on the same role for Oxfordshire after Local Government Reorganisation in 1974.  He inherited responsibility for the Henry Taunt (1842-1922) photograph collection and that became the nucleus of what is now at Oxfordshire History Centre one of the largest picture collections in local authority hands; his own contribution to that collection now runs to well over 10.000 images. He started work in the same month that BBC Radio Oxford began broadcasting and local radio tapes became a core element of a substantial oral history collection. In 1990, Oxfordshire County Council took the opportunity to co-locate many library, museum, archaeology, archive and countryside functions in Oxford Central Library and Malcolm became Head of the Centre for Oxfordshire Studies until he retired in 2008. The Centre attracted large numbers of visitors, especially family historians, and the challenges presented by an assortment of incompatible databases were finally resolved with the launch of the Heritage Search website in 2005. The onset of digitisation proved invaluable in getting collections out to the public and an early success was a joint project between the County Council and Historic England to reunite virtually separated elements of the Taunt collection.

Malcolm has published extensively on the local history of Oxford and Oxfordshire, and he compiled twelve On Foot in Oxford town trails between 1973 and 1987. There had been little research into the modern history of the city in the 1970s and he studied the development of Oxford’s Victorian suburbs for a PhD awarded by Leicester University in 1985.  He had been City Archivist briefly before 1974 and his team continued to produce documents for consultation in the Central Library for some years, trundling them through Queen Street on a sack truck!  In retirement, he discussed the long-standing issue of uncatalogued archive material in the Town Hall with Debbie Dance and she launched an OPT campaign which encouraged the City Council to appoint a part-time archivist who went on to make those records available. Debbie had always envisaged publishing updates of the On Foot in Oxford trails and she commissioned Malcolm to write six Oxford Heritage Walks books covering the city centre, published by OPT between 2013 and 2020. He and Edith Gollnast, the illustrator of those books, were elected Vice-Presidents of OPT in 2021.

Malcolm was elected a Fellow of the Society of Antiquaries of London in 1999. Oxfordshire Family History Society recognised his long-term support for local family historians, which included five summers of churchyard recording, by making him Vice-President and, in 2020, President of the Society. In 2021, the British Association for Local History presented him with a life-time personal achievement award for his work in Oxfordshire.