Was in a dire TV series once, in which the lead was Tim 'David Archer' Bentinck prancing around on a horse.
As a mere specialist extra I didn't have any lines and just had to make lots of bangs and smoke and sometimes appear dead. None of which was a problem. The food - both in qauality and quantity - was superb, and the pay wasn't bad either.
As a specialist I didn't need an Equity card (the UK equivalent to SAG), so no major career doors opened (thank gawd - because, food and tea aside, film-making is the most balls-achingly dull procedure, and those involved seem largely to be twats).