An investigation has been launched by the National Trust after a fire broke out yesterday at Clandon Park House in Surrey, a Grade I listed mansion owned by the trust.

At least 80 firefighters fought the blaze, which is thought to have started in the basement at about 4pm yesterday before spreading to the roof. It has gutted at least one wing of the 1720 mansion but the true damage of the fire has yet to be ascertained.

Items from inside the house were removed from the ground and middle floor by conservators.

Helen Ghosh, director general of the National Trust, said: “The most important thing for me is that no-one has been hurt in this awful fire and that everyone is safe.

“But it has been heart-breaking to witness the terrible damage to this wonderful mansion, which means so much, to so many people.

“This will come as a terrible shock and a devastating personal blow to all our devoted staff and volunteers.

“We’ll continue to work closely with the fire brigade, who are working hard to bring the blaze under control. We’d like to thank them again for their efforts.”

Ghosh said that there is "perhaps one roon that is relatively untouched but, other than that, the interior is extensively damaged".

She added that the exterior walls are still standing, and they have been able to save some significant items from inside the house, but "not everything that we wanted to save".

A spokesman for Surrey Fire and Rescue said this morning: “Fire crews are still tackling the Clandon Park blaze but the operation is now being scaled back now – around 30 firefighters, six engines including an aerial ladder platform and a high volume pump remain on the scene.

“Most of the inside of Clandon Park has been destroyed by the blaze but firefighters and staff from the National Trust have managed to save some paintings and historic furniture from inside.”

The National Trust is asking visitors not to come to the park.