Kate's date with brother Joss for Iris film premiere

Titanic star Kate Winslet arrived at the premiere of her new film tonight with a new man on her arm her younger brother Joss.

The 26-year-old actress, who is dating American Beauty director Sam Mendes, looked stunning in a revealing white jacket and black trousers as she arrived for the UK premiere of Iris.

Also starring Dame Judi Dench and Jim Broadbent, it is the touching love story of novelist and philosopher Iris Murdoch and her husband John Bayley.

It traces the writer’s life from her early days as a young novelist through her descent into Alzheimer’s disease until her untimely death in 1999.

Winslet plays the writer in her early days while Dame Judi portrays the novelist through middle-age.

Winslet said of the role: ‘‘It is hard because Iris was such an intellectual and I am not and when you have Dame Judi portraying her in later life it is quite frightening and you know there is a lot to live up to.’’

She added: ‘‘I would suggest people going to see it take a box of tissues as it will make you laugh, but will also make you cry.’’

Winslet, who recently divorced Jim Threapleton - father of her baby Mia - said she was looking forward to the screening, adding that she had brought her whole family along for support.

‘‘My brother is my date tonight,’’ she said.

Dame Judi agreed that portraying the novelist had been difficult. One of her main concerns had been the difference in height between Winslet and a young Murdoch and herself as the older version.

Also present at tonight’s premiere was Weakest Link host Ann Robinson, who is the vice president of the Alzheimer’s Association.

She said: ‘‘I like this film because it shows that clever people also suffer from Alzheimer’s. It happened to my mother who had a very sharp brain but deteriorated terribly.’’

Others attending the screening at the Curzon Cinema in London’s Mayfair included the British Prime Minister’s wife Cherie Blair who was with her son Euan. He was accompanied by a female friend.

TV chef Nigella Lawson and comic Harry Enfield were also among the stars attending.