Restoration of the room George IV created at the Royal Pavilion in Brighton when he finally became king following debt-ridden years as the Prince of Wales, is almost complete after three years of work.

The saloon, dating from 1823, heaves with crimson and gold silk, with silver walls, golden dragons, palm trees, winged solar disks, an explosion of sunflowers and a carpet reminiscent of a volcanic eruption. There is more to come, but the room is already blindingly bright enough to strike the viewer like a blow between the eyes.

“It was the ultimate expression of his taste, and it is quite something, certainly,” said David Beevers, the keeper of the Royal Pavilion. “The work was carried out by Robert Jones, a man of genius, and it is his masterpiece – but you do wonder if he was on something.”

Recreating every element of the room took years of research. When Brighton council paid Queen Victoria £50,000 for the pavilion it expected to get the lot, not only the extraordinary circular-domed Silver Room but all the other contents of the mind-boggling fantasy palace her uncle had created from a modest farmhouse near the sea.

Instead, the council got a stripped out shell, with everything that had been movable, from carpets and rolls of unused wallpaper to fabrics and door handles, carted away. Some items were returned in the 20th century, some are still in storage in other royal palaces, and some, like the fireplace and chandeliers from the Silver Room, are in use at Buckingham Palace.

Blindingly bright: the saloon at Brighton pavilion in 2010, before the restoration. Photograph: Royal Pavilion & Museums/Jim Holden

Beevers is in awe of the years the textile historian Annabel Westman put into tracking down the pattern for the crimson silk woven with flowers and golden birds. The 19th-century inventory said simply “his Majesty’s Geranium and Gold Colour”, but Richard Humphries, a senior member of a company of family-owned weavers in Sudbury, remembered a black and white photograph he had taken more than 50 years earlier of a similar fabric at another weavers.

From that they traced a sample – first spotted in a colour photograph in a book in the V&A shop – in the museum’s vast design archives. They then learned of a scrap framed on the wall of the upholstery workshop in Windsor castle, saved from a roll that had been used to upholster a set of Victorian chairs. The miraculous survivor was used as the pattern for 250 metres woven in Sudbury for the wall panels and curtains: they are very, very, bright.

The walls look as if they are covered in a fancy paper, but it is made up of 17,000 hand-stencilled diamond shapes, decorated with £10,000-worth of platinum leaf. Silver would have tarnished, Beevers said solemnly.

The room, he admits, is not to everyone’s taste but he adores it. Before it reopens to visitors this autumn it will have a replica sofa in the centre, so visitors can sit and recover from the shock.

The staggering carpet, a swirling kaleidoscope of flowers, stars, dragons and exotic Chinese birds, had to be reinvented from the hazy detail in a 19th-century watercolour by Anne Sowden, artist and glass conservator for the pavilion, as her last challenge before retirement.

The gilder, Norman Stevens, who hand-burnished thousands of tiny beads for the wall panel edging strips, is also about to retire.

The Robert Jones saloon from Nash’s Views. Photograph: Brighton Museums

The restoration cost £380,000, a sum raised from outside sources rather than paid for by the council. It was a bargain basement price for such a project because almost all the work was done in-house – something increasingly rare in museums.

Beevers’ only lament was that so many members of his remarkable team were about to retire, their centuries of combined skills lost to the pavilion forever. “There are other rooms, other projects – how we are going to manage without these people I just do not know.”

• The caption of the second picture was amended on 3 September 2018 because an earlier version said it was of the restored saloon. The picture was taken in 2010, before the restoration.