Hackney Council rushed through an extra £3.4million payment to contractors restoring the town hall to save the entire refurb from going under, the Gazette can reveal.

It turns out more money is needed than the £12.5m already spent on the work, which started in October 2014.

The total sum now lies at £16m.

Hackney says the additional work wasn’t originally planned, came about because designs changed, or was “not apparent” when the tender was approved in December 2015.

The scale of the problems were documented in a report ahead of a finance meeting at the town hall, which also revealed an extra £440,000 was spent on restoring marble staircases in April last year.

Bizarrely the papers also claim “changes in technology” were a contributing factor to the additional works. As a result, some work that is already finished is having to be torn out and re-done.

The £3.5million cash splash was rushed through in December by Hackney’s group director of finance Ian Williams under his delegated powers – meaning councillors didn’t get a say.

His report said: “The report was authorised due to the urgency of confirming adjustments and amendments to the buildings detailed design and therefore the expenditure on the project.

“Had the recommendations been postponed, this would have placed the works programme at risk and the project would have come to a halt mid December 2016 due to imminent shortfall in authority to spend.”

The money is being taken from the council’s capital budget and will not affect funding for other services. It will pay for a range of things, including £115,000 on renovating the council chamber. More than £545,000 will be spent on building costs and £292,000 will pay for “heritage restoration”, which includes sprucing up the mayor’s cabinet and its marble and bronze plaques.

A little over £3.3m of the extra cash will go to main contractor Geoffrey Osborne Ltd, which includes £350,000 of contingency money that had already been put aside. That company’s contract now totals £15.5m.

The other £110,000 will go to West Heath Developments Ltd for more work to the marble staircases, less than

a year after the April payment.

A council spokesman said the town hall was one of the finest Art Deco buildings in east London and its restoration would reduce the number of other premises it leased. He also said the money was coming from the capital pot and not being taken from other services.

He added: “The additional costs are due to changes in the scope of the works which is not unusual for a historic building and a project of this size. These necessary changes will prevent further disruptive building works from taking place in the future.”