Experts have put the three-feet high angel into a freezer in the hope of killing off an infestation of death watch beetles.

The beetles, which could destroy the carving if left unchecked, should die in the -50C conditions.

Alan Micklethwaite, head of the cathedral's sculpture and conservation department, said freezing was the most reliable treatment.

We have treated quite a lot of objects in this way and it has been successful every time Chris Robinson, university technician

He said: "You could treat it with a pesticide...but that has the problem of not knowing if the whole object has been properly impregnated with the pesticide so it's not guaranteed to kill everything.

"And the substance is toxic so it can become hazardous as well."

Hypothermia death

The angel has been put in an industrial freezer at the University of Lincoln's specialist conservation department

University technician Chris Robinson said: "It goes down to minus 50, which is way below anything the insects would experience normally, and that is enough to kill them, basically of hypothermia.

"It is safe for the people who are carrying out the procedure and it will mean the object is not coated in toxic chemicals which may cause a health hazard in the future.

"We have treated quite a lot of objects in this way and it has been successful every time."