WORK to begin repairing and restoring a set of medieval stained glass windows at Lincoln Cathedral will begin next summer.

The cathedral's works department is planning a £400,000 restoration of all four lancets underneath the Bishop's Eye Window, in the South Transept.

As reported in the Echo, a 13th-century medallion depicting Moses in a Biblical scene in one of the panels, was smashed into pieces two years ago as a would-be thief fled.

A modern copy was installed after the incident and the original will eventually be put back in.

Glazier Tom Küpper, 47, said each lancet would take about 12 months to restore.

"Once restored the windows will be isothermally glazed to protect them," he said.

"The hole in the broken window measures 39cm by 38cm in a medallion which is 76cm by 84cm.

"Soon after it was smashed we collected the pieces off the ground – we have 98 per cent of all of the pieces.

"So it's a question of deciding which of these we can put back in and which need replacing."

Mr Küpper added that the windows undergo a period of testing before any conservation or restoration work can begin.

"The glass from the lancets would most definitely have been made in France or elsewhere in Europe – they were 50 or 60 years ahead of what was happening here," he said.

"Master glaziers would have come up with designs of windows to sell to the clergy.

"You often see links between the Old and the New Testaments – Jonah coming out of the belly of the whale after three days and Christ rising after three days, as if in prophesy.

"Occasionally, you will see a medieval glazier's thumb print in the glass like an accidental signature but that's very rare."

The detail of Moses shows him with others in his typical white and purple garment holding his staff with which he led the Hebrews for 40 years through the desert.

The section of the window was damaged when someone hid in the cathedral after closing time but then triggered alarms.

He climbed 15ft up a wall in the South Transept and escaped through the hole in the window.

The cathedral fabric fund is one of the chosen charities of the Mayor of Lincoln, Geoffrey Kirby, who is also a tour guide at the historic building.

"It is good news that work is expected to begin in the South Transept next summer," he said.

"But work on the cathedral is always ongoing. It's like the Forth Bridge. You get to the end and then you have to start all over again."