The award by Wellington Town Council is in recognition of his role in putting the town's heritage in the public eye and detailing many aspects of its past in numerous books, articles, and talks.
"I'm more than chuffed," said Wellington-born Allan, 70, who started collating information on the town when he was just 15.
"I really am proud. What I am doing is to try to tell as much as I can about Wellington's history, its people, its businesses, and how it developed, so the information is there for people in the future, let alone people now."
He said it was humbling to receive what amounted to a lifetime achievement award.
The key was "presented" to him virtually at a town council meeting held on Zoom and is currently being engraved.
"The key is symbolic – it doesn't open anything," he said.
Founder chairman of Wellington History Group, Allan has edited 28 issues of the group’s magazine as well as writing more than 40 books on subjects including Wellington’s pubs and breweries, the Great War and The Wrekin.
He retired from researching and archiving the town's history earlier this year.
Allan, who lives in Priorslee, pinpoints two key events in 1965 which shaped what was to follow.
One was a comment by his history teacher at Wellington Grammar School in his end-of-term report, that he was "interested & intelligent but blithely inaccurate."
"It’s a comment which has dogged me all my life, to the extent that earlier this year Councillor Anthony Lowe (former Wellington mayor) noted my research as ‘forensically accurate’! My excuse is that, if people are going to be so kind as to buy my books, come to my talks and read my magazine articles, the very least they can expect is fact rather than unsupported fiction.
"The second event was my father telling me about the headstone in the churchyard of All Saints’ parish churchyard. It records the death of four children by explosion in March 1839. They were the offspring of my great-great-grandfather who ran a coal mine at Newdale.
"All my father could tell me was the family story handed down over the years. He suggested I try to find out exactly what happened. I soon found out that the story differed from official reports. So, armed with the ‘blithely inaccurate’ stigma, I made a promise to myself that I would do my best to avoid unsupported speculation.
"Then I decided to find out more about the lives of my ancestors, and the history of Wellington."
Wellington mayor Pat Fairclough said: "Allan is a Wellingtonian committed to writing all the unique history of the town and keeping its heritage alive.
"To my mind he has been a wonderful friend to Wellington Town Council because his loyalty predates Telford unitary authority and even Telford new town."