Pilgrim (Baczkiewicz)

Pilgrim is a fantasy radio series by Sebastian Baczkiewicz and produced by BBC Radio and starring Paul Hilton as William Palmer, known as Pilgrim. It is a tale of a hero cursed with immortality and forced to wander for eternity between the worlds of magic and mortals. The first series was first broadcast on Radio 4 in 2008.
Premise.
In 1185, while making a pilgrimage to Canterbury, William Palmer happens to mention in conversation that he hopes the Church in England will soon eradicate the foolish belief in the Otherworld. Unfortunately for William, his fellow pilgrim angrily reveales himself to be the king of the Greyfolk and places a curse on him that condemns him to roam endlessly between the two worlds. Known as Pilgrim, his mission is to maintain the uneasy balance between the worlds and to protect the human race from the enemy whose existence it stubbornly refuses to acknowledge. He undertakes a series of quests in the hope that the curse will be lifted, and finds himself, centuries later, in modern times.
Episodes.
Series 9 ("The Timbermoor Imp").
First broadcast on BBC Radio 4 in October 2020 and billed as "a Hallowe'en adventure for the immortal mediator".