Opponents of a two-storey roof development on their unspoilt art deco block in Highgate hope to club together to buy out the entire building.

Leaseholders at Northwood Hall in Hornsey Lane say the move would delay the building works proposed by owner and developer Triplark, which could be visible from Hampstead Heath and which they fear would ruin the building’s distinctive style.

One resident told the Ham&High: “I bought into that building because I have a real love for art deco architecture.

“So many other art deco buildings in the UK have already been victims of roof extensions but ours has retained a look that is more or less the same since it was built in 1935.”

Another of their objections stems from the planning agent’s links to two controversial pub demolitions.

KR Planning put in a bid on behalf of developer CLTX Ltd to demolish the Carlton Tavern in Maida Vale three months before it was knocked down without planning permission in April 2015, sparking national outrage.

And both KR Planning and architect Brooks Murray were involved in the attempted development of the Winchester Tavern in Archway Road, which was turned down by councillors.

Kieran Rafferty of KR Planning said the demolition was not his firm’s doing and called it “regrettable”. He added: “Both myself and Brooks Murray Architects have severed all ties with [the property owner].

“With such a wide range of clients, building types and forms, it’s not surprising that outcomes are not always popular with everybody.”

Other leaseholders support the development, despite aesthetic reservations, welcoming Brooks Murray’s promise to do much-needed refurbishment work to the building free of charge.

But the protesters hope to change the minds of a critical mass – 50 per cent of leaseholders – so they can trigger the process to buy the freehold.

Behind closed doors, the building has a lively history of bitter internal politics.

The freehold bid is the latest chapter in a lengthy cold war between two different leaseholder factions, dating back to a controversial heating refit. At the moment, 30 of the building’s 194 flats either refuse to be hooked up to the new system or refuse to pay service charges, which has sparked legal action on both sides.

The leaseholders’ Right to Manage (RTM) company voted in July 2015 not to take the builders to court over problems with that refurb. But the poll proved so contentious the company’s directors decided they needed a fresh pair of hands to manage the company: Bruce Maunder Taylor, who was appointed by a tribunal.

Mr Maunder Taylor’s main challenger for the job was David Wismayer, who had favoured suing the engineers, with both men commanding fierce support from some and opposition from others.

Now the leaseholders leading the buyout bid say they have a “white knight” investor, Lindmead Ltd, which would help shoulder the costs of the project.

But other leaseholders see Lindmead’s involvement as a continuation of the building’s long-running power struggle because one of its directors, Geoffrey Gay, is a business associate of Mr Wismayer – the pair are both listed as directors for another firm, Bestwish Ltd, on Companies House.

Brooks Murray senior architect Timor Tzur said: “We have proposed to do a massive amount of work that needs to be done, restoring original features.

“The council’s planning officers were actually quite happy with our approach, which doesn’t mimic the style but does follow the same language.”

“The project is internally controversial due to years of battles between different groups trying to take over the building but that is not our domain.”

She added a smaller one-storey extension would be unviable because space standards have increased since the building’s construction.