Henry Linchon has died recently. He was one of three co-authors of The Holy Blood and Holy Grail, which introduced the theories that would be made more notable in pop culture in The Da Vinci Code. In addition to being an actor, he was a co-writer on the original series of Doctor Who and helped to create the Yeti and The Great Intelligence as well as The Quarks with his partner Mervyn Haisman.
With his passing, all the writers of Doctor Who from the 1960s are gone.
https://scifibulletin.com/2022/02/25/rip-henry-lincoln/