Victoria Smurfit is Grant's co-star

Grant joked he had been interviewed 39 times during the day and he had been asked about Hurley 39 times, but admitted clamming up each time and giving nothing away.

Grant said: "I have always wanted to be a dad, it would be marvellous to be a father."

Good run

But he refused to reveal whether he had visited Hurley and her new arrival Damian.

Rachel Weisz, Toni Collette and Victoria Smurfit co-star in About a Boy, which is directed by Chris and Paul Weitz, who also made American Pie.

The comedy-drama is an adaptation of Nick Hornby's best-selling novel.

Grant will be hoping the movie continues his recent good run at the box office.

He was in last year's Bridget Jones's Diary, which took more than �41m in the UK alone, as well as starring in other recent hits Small Time Crooks and Notting Hill.

Grant became internationally famous after the success of 1994's Four Weddings and a Funeral and his relationship with Liz Hurley became front page news.

The pair split in May 2000 after 13 years together but have remained good friends.

Hornby has had three novels turned into films

The 41-year-old had jetted into London from the New York set of his new movie Two Weeks' Notice, which co-stars Sandra Bullock.

Best-seller

For Hornby, this is the third of his novels to be made into a movie, after Fever Pitch and High Fidelity.

The 45-year-old is one of the UK's top-selling authors.

His latest novel, How To Be Good, was recently named the UK's favourite work of fiction at the WH Smith Book Awards, the only major book prize to be voted for by the public.

About A Boy is a departure for the directing Weitz brothers.

Their first film was the high school comedy American Pie, which was a massive hit in 1999, taking more than $100m (�69.2m) in the US.

About A Boy will be released in the UK on 26 April.