Zoe Wanamaker and Ken Livingstone this week attended the launch of a new five-year partnership between the National Theatre and Philips to renew the external and internal lighting of the South Bank landmark.
Monday's ceremony marked the completion of the first phase of the new external lighting scheme. Philips says that their new system delivers a 70 per cent reduction in the energy required to light the National Theatre's flytowers.
Once the lighting has been replaced throughout the building with new energy-efficient bulbs the theatre hopes to achieve an annual saving of £100,000 to be reinvested in theatrical productions.
"This is a really great day for the National," director Nick Hytner told guests at the switching-on ceremony at Somerset House.
"We started lighting the building in colour a few years ago and many people have told me how much they like it. I think we probably get more compliments on our lighting that our shows!
"People have really grown to love Denys Lasdun's National Theatre over the past few years because of the lighting and I think from now on I can see an even bigger postbag coming my way."
He added: "It's a huge win for us – it's good for the planet and it's good for art."
In his speech the Mayor of London Ken Livingstone recalled being present at the opening of the National Theatre building 31 years ago.
He told guests: "If we have the will, we can create a world that is sustainable and a pleasure to live in. We don't have to worsen our quality of life; we can still see great theatre and the enivronment in which we live can be sustained."
Mr Livingstone used the occasion to launch a new partnership in the London theatre industry to improve energy efficiency in arts venues across the capital.
The Mayor was joined at the launch by actress Zoe Wanamaker who has just started rehearsals for Much Ado About Nothing which opens in the Olivier Theatre at the National on 10 December.