Breaking in to the bishop's icehouse in Auckland Park

But the icehouse in Auckland Park, which enabled the poshest chilled desserts to be served to the Bishop of Durham’s guests in his nearby palace at Bishop Auckland, will reveal much more about the life and times of people in the late 18th Century as archaeologists explore its construction and delve into the debris on its floor.

The first hole is made in the 1970s brickwork that blocked the entrance to the Auckland Park icehouse

There was almost as much excitement yesterday in Auckland Park as when Tutankhamun’s tomb was entered for the first time in 1922. The entrance to the icehouse had been bricked up in the 1970s when there was also a wooden door preventing people from gaining access so it was several generations since it had last seen the light of day.

With the temperature outside nudging up towards a sweltering 30 degrees, when the first rays of the sun were let in, they revealed that the egg-shaped subterranean chamber was in almost perfect condition.

“I’m amazed it is so intact,” said Professor Chris Gerrard, of Durham University. “Looking at the top of it, I would have thought there would have been root damage or animal burrows in it, but it is brilliantly preserved – you could load it up with ice today.”

The icehouse was built between 1780 and 1820 when there was a craze for chilled desserts among the upper classes to show off their wealth. In winter, ice would have been carted off the nearby fishponds and stored, probably between layers of insulating straw, in the cool chamber where it could last for a couple of years until it was required in the bishop’s kitchen – the ice was never eaten but it was used to create novel desserts like ice cream.

Prof Chris Gerrard, of Durham University, and John Castling, of The Auckland Project, with stonemasons breaking into the icehouse behind them

The icehouse is located inside a hillock in Auckland Park next to Coundon Burn. The chamber appears to be at least three metres deep. Among the debris on its floor was the old wooden door and the Fosters and Carling cans that must have been dropped when it was sealed up in the 1970s. When the debris is sifted through, it is hoped that a drainage system will emerge through which meltwater would have run into the burn.

The archaeology carried out by Durham University students alongside The Auckland Project first revealed that the top of the icehouse dome was insulated by a 40cm-thick layer of clay.

“I’ve learned about how it was built – I didn’t know it was built of handmade bricks,” said the professor. “I have learned about its shape and its capacity, and I am surprised that it doesn’t have a staircase going down to the bottom. There must have been a rope ladder or stepladder going down.

“And I have learned the importance that the bishop must have placed on having the right, elite foods on his table because it is a lot of effort to go to build something like this.”

John Castling, the archaeology curator at The Auckland Project, said: “It is connected to a series of alterations that were made in the park in the 18th Century when the bishops had become wealthy due to coalmining. They were looking at ways of turning the medieval deerpark, which had fallen into disrepair, into something in which they could display their wealth.”

And there was nothing more ostentatious than serving your guests ice cream – in strange flavours like artichoke or parmesan – or fashionable chilled fruit.

However as techniques improved – ice was imported from Scandinavia and then ways were found of making it locally before refrigerators were invented – icehouses were no longer needed and most were allowed to collapse.

“It is basically untouched both inside and out, which says it was abandoned because it was no longer needed rather than it wasn’t working properly,” said Mr Castling.

A 3D laser scan of the chamber is to be made, but at the moment the entrance is being secured so no human or animal could tumble in.

The icehouse opens up for inspection