According to the official Bard's Tale: Tales of the Unknown Clue Book, Lord Garrick was the leader of a party of adventurers who fought their way to the uppermost level of Mangar's Tower where they perished.
Obviously, Garrick was a paladin. The clue book consists mainly of his diary, but the introduction by his old friend Pellis tells the reader a bit more about him. He was viscount of Skara Brae's neighbour city, Hamelon. Like others, he became trapped in Skara Brae by the snowdrift Mangar had conjured.
"The Bard's Tale leichtgemacht", in: Happy Computer Sonderheft 24: Spiele-Sonderheft, pp. 27-34. (A German translation by Anatol Locker and Heinrich Lenhardt, authorized by Electronic Arts)