Tensions are running high in Gillett Square, where controversy surrounds a £2m project to revamp affordable workspace.

Hackney Co-Operative Developments (HCD) has applied for planning permission to put a clear polycarbonate façade and an extra two floors on the terrace in Bradbury Street, which overlooks the square.

But opponents fear it could force out businesses and lead to gentrification, and that its plastic design could be a risky move in the wake of the Grenfell Tower disaster.

Police are investigating an arson attack last week that saw furniture destroyed on Kaffa Coffee’s stall.

Architects and heritage experts from the Dalston Conservation Area Advisory Committee have complained the proposals are “too large and too high”, and the “dominant pitched form of the roof extension is inappropriate in the predominantly Victorian context and would damage the quality and character of the conservation area”.

Since the application was lodged, some 1,000 people have added their names to a 4,000-strong petition set up last summer calling on the council to “stop the square’s destruction”, and list it as an asset of community value.

HCD chief exec Edward Quigley said the petition was misleading and had just been “repurposed” from one about a car park.

But HCD’s former managing director from 1996 to 2012, Adam Hart, said both plans were “profoundly destructive”.

“The HCD plans involve a building in the middle of the square,” he said. “They are arguing this might be temporary, but it could be a permanent placement. It comes down to the same thing: that the square is under threat.”

While publicity flyers distributed by HCD in October promised: “We won’t force out any of our current businesses”, a leaked report to HCD’s general council in March stated: “Tenants who are not moving to Woodberry Down will be served notice to make sure the works can commence on time.”

Mr Hart told the Gazette tenants’ security of tenure is the “most notable and worrying human aspect” of the scheme, and the threat of eviction was not aligned with the core values of HCD.

But as the Gazette went to press, Mr Quigley revealed HCD’s stance had since changed.

“Bradbury Street leases will not be terminated for any tenant that wishes to be decanted to Woodberry Down or another HCD site,” he said.

“For any tenant who does not want to decant to either of the HCD options, we have given them the scope to keep their current lease intact, so that they can make their own arrangements and return to the redeveloped building following works.”

The leaked document also indicated the project could be running precariously behind schedule.

City Hall has handed out more than a million pounds to HCD to fund the project in Bradbury Street and transfer its tenants to workspace in Woodberry Down while the works are completed.

The City Hall money was meant to be spent by the end of March, but by that point HCD had still not secured planning permission or a bank loan, according to the leaked report.

A six-month extension has been granted until September 30, and Unity Trust Bank has since offered funding.

The public money had originally been earmarked to provide affordable workspace at the six-storey “Dalston Bunker” in Ashwin Street, which would have been delivered by Dalston Works – a collaboration between HCD and the Bootstrap Company.

It was one of 69 submissions for a slice of the £20m London Regeneration Fund (LRF) to “help businesses and community groups in the capital” in 2015, 24 of which were successful.

City Hall, Bootstrap and HCD have been unable to tell the Gazette exactly why or when that project fell through – but it is thought it was deemed “unviable”, and at some point the money was transferred over to the Gillett Square project.

This was part of the bid, but never mentioned when City Hall sent out a press release announcing the funding.

“Bootstrap couldn’t go ahead with its project, but was already far down the line, and in what seems to be low due diligence of the GLA, they committed funding to this other project before they even knew where they were going,” said Mr Hart.

“They didn’t make an announcement or push it open to public competition again, and frankly that’s not a proper procedure.”

HCD was required to matchfund £825,000 grant from the Greater London Authority – but now the project is expected to need as much as £2m to pull off.

HCD has refused to publish financial viability projections, and some fear that rents could rise to pay for it. Mr Quigley dismissed those concerns.