Theatre veteran Sir Peter Hall has described cuts to arts funding as "insane" in a speech at the Evening Standard theatre awards in London.
Sir Peter, who has just turned 80, was being honoured for his contribution to world theatre.
He urged an audience - packed with top actors and directors - to make "loud noises" against budget cuts.
"It's insane," Sir Peter said. "I feel really ill at the thought of over 50 years thrown away."
Sir Peter had been presented with the Golden Seagull award by his daughter Rebecca Hall, whom he will be directing in the National Theatre's Twelfth Night early next year.
After founding the Royal Shakespeare Company, Sir Peter was its artistic director for eight years. He went on to spend 11 years as director of the National Theatre.
His words were echoed by Sherlock star Benedict Cumberbatch, who predicted that a 25% arts budget cut would mean "an across the board reduction in quality".
He told the BBC: "This is an incredibly vibrant and inventive culture, and while there will always be people who will still find ways of making what they've got work, I really do fear for the general landscape of this country culturally."
Sir Michael Gambon, whose career spans stage and film, received the Lebedev Special Award for his work in British theatre.
His stage appearances include works by Shakespeare, Harold Pinter, Sir David Hare and Samuel Beckett.
Anya Reiss won the most promising playwright award for a play she wrote aged 17.
Spur of the Moment was written while she was on a young writers' course at the Royal Court and marked the first time the theatre had staged a play by someone still at school.
Isabelle Huppert, Charlotte Rampling, Tom Hollander were among the guests at the awards ceremony, hosted at the Savoy by Stephen Fry.
Martin Freeman, Adrian Lester, Miriam Margolyes, Diana Vickers, Damian Lewis and Sir Ian McKellen also attended the event.
Bruce Norris's play Clybourne Park, a study of racial prejudice in America, was named best play.
It began at London's Royal Court and will transfer to the West End next year.
The Natasha Richardson award for best actress was presented by the late star's husband, Liam Neeson.
It went to Nancy Carroll for her role as Joan in Terence Rattigan's After the Dance.
She described the award as "a big, fat sparkling cherry on an already iced lovely cake."
Rory Kinnear won the best actor prize for two Shakespearean roles, as Hamlet and Angelo in Measure for Measure.
Stephen Sondheim's Passion, staged at London's Donmar to mark his 80th birthday, beat Legally Blonde and Les Miserables to win the Ned Sherrin award for best musical.
Best director went to Howard Davies for The White Guard, a new version of Mikhail Bulgakov's Russian work, and Arthur Miller drama, All My Sons.
He previously won the award in 1998 for Flight and The Iceman Cometh.
A special "shooting star" editor's award was won by Daniel Kaluuya, 21, for his performance in Roy Williams's boxing drama Sucker Punch.
And the fastest-selling show ever produced at the Barbican, You Me Bum Bum Train, won the Milton Shulman award for outstanding newcomer.
One of its creators, Kate Bond, thanked the 200 volunteers who had turned up each night to make the drama work by playing roles such as diners in a sushi bar and airport passengers.
The best design prize went to Miriam Buether, for creating a boxing ring in the middle of the Royal Court for Sucker Punch and for transforming the National's Cottesloe theatre for Earthquakes in London.
Buether received her award from collaborative artists Gilbert and George.