"We have got a way to go. We have started building. It will all be down in ten days' time but we have still got just under £1 million to find by March next year," said Young Vic director David Lan.
The ceremony also featured Joseph Fiennes, who recalled his time as an usher at the Waterloo theatre: "I had the opportunity to watch – as I was an usher – Bob Peck, Helen Mirren and Trevor Nunn. I can't tell you how important that was.
"I can speak for many people who are writers or directors, performers or stage crew and it all started here. For me it is a wonderful opportunity to join David and his team in realising the new future for the Young Vic.
"I think it is really important to have a flagship theatre like the Young Vic and one that reflects the dynamic and refreshing work that is going on inside."
The redesign is by Haworth Tompkins and design team Studio Todd Lecat. Building work will be completed by autumn 2006.