Which British actor played the role of Withnail in the classic British film 'Withnail and I'?

'Withnail and I' is a 1987 British black comedy film written and directed by Bruce Robinson. Based on Robinson's life in London in the late 1960s, the plot follows two unemployed young actors, Withnail (Richard E. Grant) and I (Paul McGann) who live in a squalid flat in Camden Town in 1969 while squandering their finances on alcohol. Needing a holiday, they obtain the key to a country cottage in the Lake District belonging to Withnail's lecherous gay uncle Monty and drive there. The holiday is less recuperative than they expected.

Withnail and I was Grant's first film and launched him into a successful career. The film also featured performances by Richard Griffiths as Withnail's Uncle Monty and Ralph Brown as Danny the drug dealer. The film has tragic and comic elements (particularly farce) and is notable for its period music and many quotable lines. It has been described as "one of Britain's biggest cult films".