They gave her the biggest roasting since Madonna took her first curtain call in British theatreland and critics said the pop superstar was "More Mechanical Girl than Material Girl."

"Sorry Scully but you have lost your X-Appeal," The Daily Mail said of Anderson's performance in Michael Weller's play "What The Night is For." It was a far cry from her devoted following as Agent Scully in the cult television series.

London has attracted a steady stream of Hollywood stars from Nicole Kidman to Gwyneth Paltrow and Matt Damon, eagerly accepting stage roles in Britain to boost their acting credentials back home.

They were generally welcomed for bringing Tinseltown glitter to the London stage, hit heavily by the lack of tourist visitors to Britain after last year's September 11 attacks.

The stars are happy to abandon luxury film set trailers for a pokey little dressing room. But what attracts them? Matt Wolf, London theatre critic for Hollywood's Variety trade paper, told Reuters: "It certainly isn't the money. They could make more in a half-hour photo shot. It is the exoticism of London. If you make it in London, everyone back home is extremely impressed."

For some the gamble paid off -- Nicole Kidman was hailed as "pure theatrical viagra" in "The Blue Room" -- but theatre critics are not always so kind, telling Madonna she should stick to the day job after her debut in May in "Up for Grabs."

Anderson came in for a severe grilling. "This one is a pure, unmitigated stinker," said The Daily Telegraph which called her performance "pitifully exposed and inadequate."

"She is woefully uninvolving," said the Financial Times. "Does Anderson's voice have no capacity for heart-catching uplift, no sudden changes of volume?"

But The Guardian was much kinder, deciding Anderson's two-hander about adultery with British classical actor Roger Allam was superbly played. "Gillian Anderson happily swaps Agent Scully for a role that requires her to do an emotional striptease."

Anderson was frank about her first night performance, telling the Evening Standard: "Bloody hell -- the first couple of scenes just sucked, they really sucked.

"It wasn't that fun for the first few scenes but then we started to have fun -- and the second act felt really good. But it was so odd, so odd. When I get nervous I get a bit stiff."