THE “most important historic building after the Royal Pavilion” is returning to its roots after councillors granted permission to convert it into a luxury home.

Grade I listed Marlborough House in the Old Steine, Brighton, will be converted into a six-bedroom luxury home after its change of use from offices was granted planning permission.

Councillors warned that failing to take action now could see the historic gem fall into “disrepair and decay”.

The home was built in 1765 and was owned by both the third Duke of Marlborough and William Hamilton MP who invited the Prince of Wales to stay in 1789 and 1795.

The building was added to Historic England’s at risk register in 2014 and was most recently used as offices but has empty for the past 20 years.

The latest plans have been brought forward by Eurofile Pension Fund which have owned the property since 2002.

The luxury home would have a family room, TV room, kitchen, utility, plunge pool, sauna and wine cellar in the basement with a drawing room, dining room, cloak room, gymnasium and music room on the ground floor.

A first floor would have a master bedroom with en-suite and dressing room, five additional family or guest bedrooms, a family bathroom and a gallery while the second floor would accommodate staff and a games room.

Speaking at yesterday’s planning meeting, Conservative councillor Lee Wares said: “We have to be mindful this building is slowly falling into disrepair and decay, we should be welcoming somebody trying to bring the building back as much as they can to its former glory.”

Green councillor Leo Littman said he had reservations of converting office space into housing and large homes for just one occupier - but this particular project struck him as both “sustainable” and not harmful to the historic building.

Labour councillor Les Hamilton said: “There is talk about a deferral but with most of these old buildings, the longer you leave them then the worst the deterioration and I don’t think we can leave them any longer.”

Jim Gowans said while the Conservation Advisory Group did not object to the change of use, he called for a deferral on the decision to allow a full survey to be carried out to provide assurances on the impact the plans would have on “what is after the Royal Pavilion, the most important historical building in the city of Brighton and Hove".

Conservative councillor Carol Theobald said it was a shame the building could not be opened up to the public.