Pegg (r) won rave reviews for zombie comedy Shaun of the Dead

The film, directed by former Friends star David Schwimmer, took more than �2m at the box office beating Oscar hopeful Atonement into second place.

Starring Simon Pegg and Thandie Newton, the low-budget film outshone Hollywood heavyweights including The Bourne Ultimatum and US comedy Knocked Up.

Stephen King thriller 1408, starring John Cusack, rounded out the top five.

Pegg co-wrote Run, Fatboy, Run, which sees him playing an overweight security guard trying to win back the girlfriend he abandoned at the altar five years before.

UK BOX OFFICE 1. Run, Fatboy, Run - �2.01m 2. Atonement - �1.63m 3. The Bourne Ultimatum - �1.09m 4. Knocked Up - �756,339 5. 1408 - �550,538 Source: Screen International

The comedy, which marks Schwimmer's directorial debut on the big screen, also features Simpsons star Hank Azaria and comedian Dylan Moran.

Atonement, based on the best-selling book by Booker nominee Ian McEwan, entered the charts at number two, with box office takings of �1.6m.

Both films open in the US later in the year.

Meanwhile Harry Potter and the Order of the Phoenix, remains in the top 10 - at number eight - nearly two months after it first opened.