Dr Ashdown-Hill completed his MA in Linguistics and PhD in medieval history at Essex. He also received an honorary degree from Essex in 2014. He was a longstanding supporter of the Department of History and maintained close links with the University throughout his life.
His death was announced on his website at the weekend.
Professor Alison Rowlands said: "I was extremely sad to hear the news of John's death. I have known John since 2004, when he began his PhD in our Department of History at Essex, and had the honour of delivering his oration when he was awarded an honorary doctorate by the University of Essex in 2014.
“John was a prolific author, a leading historian of the Yorkist dynasty, and a real gentleman, who combined a genuine gentleness of manner with an immense enthusiasm for the solving of historical mysteries. This enthusiasm was best exemplified in the absolutely pivotal role that John played in pinpointing the location – and confirming the identity – of the remains of King Richard III in 2012. Without John’s research into the fate of the King’s body after the Battle of Bosworth in 1485 and into the mitochondrial DNA of Richard’s descendants, it is unlikely that this major discovery could have been made."