It is a joy to rip off some wallpaper and find the last date the wall was decorated revealed underneath.

But when developers stripped off some wallpaper in a listed building in Bank Street, Maidstone, while converting it into flats, they were more than surprised by what they found.

What they had revealed was more wallpaper, but when it had been pasted on the wall, the decorators had used animal glue and had to pay a wallpaper tax of one penny for every square yard to the reigning monarch, King George II.

Landlord Jonathan Curtis enlisted the help of historic interior conservationist Allyson McDermott, who confirmed said: “It was the first example of its design I have seen.”

In her report on the find, she said: “Both the results of the analysis and examination of the stylistic context confirm that this is an important and unusual mid-18th century paper.”

The wallpaper, which was found on the front wall of the property at 69 Bank Street, above Pars Supermarket, is a grisaille wallpaper, block printed in charcoal black, chalk white and umber.

It was printed on unbleached linen, known as “cartoon paper” and has a duty stamp on the back showing it was made during the reign of King George II, who was on the throne from 1683 to 1760.

Mr Curtis said: “We took out some wood panelling and it was behind there. There wasn’t a huge amount of it – about a square metre.

“The conservation officer wanted it to either be removed or preserved in situ; we chose to have it removed. There was another bit of wallpaper that was old elsewhere in the building, but they weren’t so fussed about that.”

There are only a few other examples of wallpaper from the period preserved, one of which was found in St Paul’s Cathedral and the other in Temple Newsam House in Leeds, but the Leeds example was too small to see the full pattern.

Wallpaper discovered at the rear of the property was also of interest to historians, dating from the 19th century.

Maidstone council gave listed building consent to the plans by applicants Stanton Properties to convert the top floors of the building into a one-bedroom flat and four two-bedroom flats last year.

Planners have asked to keep a watching brief on the repairs to the fabric of the building and the situation with the wallpaper.