By Tim Masters
Entertainment correspondent, BBC News
Anne-Marie Duff and Andy Serkis celebrate their award wins
Anne-Marie Duff and Andy Serkis have won the best acting prizes at the Evening Standard British Film Awards.
Duff took the best actress award for her role as John Lennon's mother in Nowhere Boy, beating Carey Mulligan who is Oscar-nominated for An Education.
Andy Serkis won best actor for his role as Ian Dury in the punk biopic Sex & Drugs & Rock & Roll.
Gritty drama Fish Tank, by Oscar and Bafta winner Andrea Arnold, took the best film prize.
The awards took place at the London Film Museum on Monday night.
There was a tense moment when Duff, who is expecting her first child with her husband James McAvoy, slipped as she climbed onto the podium to accept her award.
Duff thanked McAvoy, who was in the audience, for allowing her to take her work "far too seriously".
She said: "I'd really like to be Mrs McAvoy for a minute and say thank you for seriously having to live with a flame-haired broken-hearted banjo player for quite some time."
Duff shares a laugh with David Morrissey after she tripped over
Duff was one of several actresses to slip on the podium, so Andy Serkis made a joke of it and threw himself down the stairs as he went to collect his best actor gong.
Serkis dedicated his award to Dury, saying: "Ian wherever you are, this is for you."
Serkis told the BBC that the film had been getting a "great response" from hardcore Dury fans.
"It's been a really extraordinary job from the word go - it chimes in with the 10 year anniversary of Ian's death this year.
"It's really great that people start to investigate his music once again - that's actually one of the joys of it."
Veteran director and cinematographer Nicolas Roeg won a special award for his contribution to film.
He was honoured for his work including Walkabout, The Man Who Fell To Earth, and Don't Look Now.
Sacha Baron Cohen appeared as himself, unusually
The award was presented by Walkabout star Jenny Agutter, who told the BBC afterwards: "I think he's a brilliant film-maker - you can't help but be affected by the work that he does. He always creates something that is completely different."
Sacha Baron Cohen won the Peter Sellers Award for comedy for his alter-ego, the Austrian fashion reporter Bruno. He received the award from the director and Monty Python star Terry Gilliam.
Baron Cohen, who appeared as himself rather than as one of his comic personas, described how he would smuggle himself into cinemas as a boy to watch Monty Python films.
Other guests at the ceremony included Coldplay frontman Chris Martin, Sarah Brown, Steve Coogan and Eva Green.
Best film Fish Tank is the latest film from Andrea Arnold, who won a Bafta for her 2006 debut Red Road. She won an Oscar for her short film Wasp in 2004. Fish Tank took the jury prize at Cannes in 2009.
The story centres on a feisty young Essex girl (Katie Jarvis) whose life is dramatically altered by the arrival of her mother's new boyfriend, played by Hunger star Michael Fassbender.
"I'm delighted. It's a huge honour," Arnold told the BBC.
"It's wonderful for the film and all the people who worked hard on the film, but I'd happily sneak away
"I don't feel any different now to when I did five years ago. It doesn't matter how many awards you get, it still feels like a massive struggle and a challenge to find the truth of what you're doing."
Fish Tank star Katie Jarvis was spotted by talent scout at a railway station
Arnold said she is now starting pre-production on her new project, an adaptation of Wuthering Heights to be shot on location in Yorkshire.
Fish Tank's lead actress Jarvis was beaten to the prize for best newcomer by Peter Strickland for his debut film Katalin Varga.
Strickland wrote and financed the revenge saga himself, and then moved from Reading to Romania to direct it.
The technical achievement award went to Barry Ackroyd for his cinematography in Iraq bomb disposal drama The Hurt Locker.
Political satire In The Loop took best screenplay, and Anvil! The story of Anvil won best documentary.
The awards are judged by five film critics, including Derek Malcolm and the Evening Standard's Andrew O'Hagan.
O'Hagan said: "This has been the best year for film in at least a decade. At every level of the business, from the poetic, independent feel of a great film like Fish Tank to the beautiful, humane brilliance of Disney Pixar's Up, there has been a flourishing in the cinematic arts that has everyone excited."