A 91-year-old former Army officer has received his doctorate from Cambridge University for creating an atlas of railway stations built in Britain.
Michael Cobb, a former Colonel from Devon, is thought to be the oldest recipient of a PhD from the university.
"It's something I wanted to do and something I loved doing. I don't know what all the fuss is about."
One university academic called his work a "remarkable piece of scholarship".
Colonel Cobb was joined at the ceremony by 40 members of his family - some of whom had travelled from as far afield as Canada, Spain and Texas.
His son, Stephen, 60, who travelled from Canada, said: "We're all very proud of him. To get a PhD at 91 is incredible. No-one else in the family has got one. It was an incredible surprise and means an awful lot to us."
A university spokesman said "The Railways of Great Britain: A Historical Atlas" was Colonel Cobb's "magnum opus" and had involved 18 years' research.
Colonel Cobb, who lives in Plymtree, Cullompton, graduated from Magdalene College, Cambridge, in 1938, joined the Army before seeing action at Dunkirk, north Africa and Italy.
He retired from the Army in 1965 and worked in mapping until his retirement in 1971. He began work on the atlas at the age of 62 and carried out the research in his own time.
Dr Richard Smith, head of the university's geography department, said the atlas is a remarkable piece of scholarship.
"It is a definitive record. It is not just of interest to the enthusiast, but a vital tool for anyone seriously interested in the economic geography and history of Great Britain. There is nothing like it."
It is thought the oldest person to receive a PhD was the Reverend Edgar Dowse who received his from Brunel University in 2004, aged 93.