Rare treasures are being uncovered for the first time in 400 years by builders working to convert historic buildings in Great Yarmouth.Experts from Norwich Castle are being called in to assess decorative wall paintings which have been exposed by workmen in North Quay, with a view to restoring and conserving them.

Rare treasures are being uncovered for the first time in 400 years by builders working to convert historic buildings in Great Yarmouth.

Experts from Norwich Castle are being called in to assess decorative wall paintings which have been exposed by workmen in North Quay, with a view to restoring and conserving them.

A rare mullion window, said to be the best example found in Norfolk for 30 years, has also been discovered at the former Advision building under a £1.5m housing renovation scheme.

Darren Barker, conservation officer at Great Yarmouth Borough Council, said the exciting finds were especially surprising because they turned up in what historians had believed was the newer part of the block.

Attention had been focussed on the next-door former Boultons furniture store, a known Merchants house dating from the 1600's century - but the discoveries were leading to a reappraisal of the whole site.

Mr Barker described as “incredibly important” fragments of paintings he believes form part of a larger frieze of heraldic shields.

He said the features were probably covered up during a Georgian refit and were perfectly preserved.

What was especially exciting about the mullion window - a type of oak window predating sash windows - was that it retained the fixings for the waxed cloth that was hung there instead of glass.

He said the paintings demonstrated it was once an incredibly high status home with the rich merchant owner enjoying views of Breydon Water, watching his ships ply their trade.

He said: “We thought the Advision part was a Victorian add-on but it is earlier and more interesting. Every week they are finding something else. It is a really exciting time capsule. The window was probably only used for 50 or 70 years and exposed 400 years later.”

He said a workman chipping away at plaster discovered the red-ochres, blues and browns of the paintings and immediately sought advice.

A crescent and a cross were the first images that were visible and work on a small section revealed a whole shield.

A few months ago a skull was found embedded in a fire place, harking back to Boulton's earlier life as a Friary. He praised Wellington Construction for their sensitive work which respected the building and its layers of history.

North Quay was once the preserve of the richest merchants whose beautiful homes had gardens which rolled down towards the water's edge. Boulton's was built in the 1650s as a five bay mansion house. It was extended in the 18th century when its owners built over the medieval row and added a rear wing. Later that century two more bays were added. It fell into disrepair in the 1990s and ranked among local eyesores. The council saved it amid controversy in 2003, purchasing Advision next door three years later.