THE kilt was everyone's delight as Glasgow actor Peter Mullan, 37, last night won the Best Actor prize at the Cannes Film Festival. The jury, chaired by Martin Scorsese, voted unanimously for his performance as a reformed alcoholic in Ken Loach's My Name is Joe.

The film, set in Glasgow, was written by Paul Laverty and funded by #500,000 of lottery money from the Scottish Arts Council and a grant from the Glasgow Film Fund.

Mullan, whose appearance on the platform wearing the kilt was greeted with rapturous applause, said that half of the prize belonged to Loach, whom he called one of the world's great film-makers.

Asked later whether he was wearing anything under his kilt - at one point on the stage he had threatened to lift it for the benefit of the cameramen - a delighted Mullan said that, like a true Scotsman, the answer was nothing.

He was wearing a dress Gordon kilt hired from Highland Dress in Sauchiehall Street and had been due to return it to them on Friday. ''I'm going to ring them tomorrow and ask them not to fine me for being late,'' he quipped. He added he was just delighted for Scotland and had never entertained the idea of winning.

''It feels great to meet and shake hands with people like Robert Duvall, Martin Scorsese, and Winona Ryder,'' he declared. Earlier, though, he confessed: ''I don't care about awards. I would not want the experience of working with Ken to be ruined by any disappointment about not getting the headmaster's approval. Working with Ken is reward enough.''

Glasgow lifted another prize when Scottish film director Lynne Ramsay, who won the short film Palme d'Or two years ago, was runner-up in the same section with her film Gasman, about two children facing up to problems caused by their parents' divorce.

Ramsay, asked whether she was a Scottish or a British director, replied that she liked to think film making was universal but she was Scottish through and through. ''I'm really happy for Peter because I'm going to see him next week for a casting session,'' she said.

She is about to start work in six weeks' time on Rat Catcher, about a Glasgow garbage strike. ''He (Mullan) is a lovely guy and his performance in My Name Is Joe was incredible,'' she added.

Mullan, who is married with two children, has had a fabulous week. His film Orphans, the first feature he has directed, and produced by Frances Higson, was in the market. He has become the most talked about actor/director in town.

He started acting 10 years ago after suffering a breakdown and was a regular with the Wildcat Theatre Company. He has also worked at Glasgow's Tron Theatre. He began making films when he was 19 and a student at Glasgow University, but when he failed to get into the National Film School he gave up his film-making ambitions.

It was not until four years ago that Mullan returned to film-making. His first was with the producer Frances Higson. It was called Close and they went on to make a second short, Good Day For Bad Guys, which won 15 awards including a Bafta Scotland prize, the best drama prize at Toronto, and the best short at the Celtic Film and Television Festival.

Orphans is their first feature film. Mullan also writes for theatre and television, had a sitcom on Channel 4 called Miles Better, and teaches.

He said of making Ken Loach's My Name Is Joe - in which he plays the title role of the reformed Glasgow alcoholic - that because of Loach's ''invisible camera'' method of filming, it was the easiest shoot he had ever been on.

''It is hard work but you enjoy it because it is so exciting every day not knowing what happens next. Most films become repetitive and boring.''

Mullan studied social and economic history and drama at university. He said his father's death the day he started there in 1977 led eventually to his suffering from depression and a breakdown.

It was this that led him into acting and to teaching drama. He worked in community centres and in the special unit at Barlinnie prison for two years.

The Palme d'Or went last night to Greek director Theo Angelopoulos for his film Eternity and a Day - about a dying author putting his affairs in order.

Runner-up was La Vita e Bella, directed by and starring Italian comedian Roberto Benigni, who stole the evening. Overjoyed with the prize - it was not clear whether he might have been under the impression he had won the Palme d'Or - he erupted on to the stage, kissing everyone and throwing himself at Martin Scorsese's feet, kissing them. The pair then embraced and Benigni proceeded to kiss all the actresses in the jury. The audience was on its feet.

British director John Boorman won the best director prize for The General, about the Irish criminal Martin Cahill who was assassinated by the IRA. He dedicated the prize to the Irish people.

One other British film, Velvet Goldmine, starring Ewan McGregor, featured in the awards. Director Tod Haynes was given the prize for the best artistic contribution.