Thursday firmly tells Morse not to drink hard spirits at lunch-time and tells Jakes, who's buying the drinks, that he'll have "a pint of Radford's" instead. Radford's is the name of the family-owned brewery featured in the 1990 "Inspector Morse" story "The Sins Of The Father".
When the young Morse was checking out Pettifor's place in Soho, one of the brass name plates by the door was for "R. Duck & Co. 4th floor. Theatrical agent". In Withnail & I, Monty describes his first agent as being one Raymond Duck...four floors up on the Charing Cross Road and never a job at the top of them...