A lengthy court battle over a mansion block with two separate heating systems has come to an end with a county court judge declaring works had been carried out unlawfully – and that the building’s manager must pay hundreds of thousands of pounds in legal costs.

Two groups of leaseholders at Northwood Hall in Highgate had sued Bruce Maunder-Taylor - the court-appointed manager of the building - and the Right-to-Manage company (RTM) of the building over a central heating project that is now five years overdue and expected to have cost more than twice its inital £2.68m budget.

Mr Maunder-Taylor must pay damages to leaseholders for failing to supply them with central heating.

One of the successful leaseholders, Philip Whale, told this newspaper: "What we have achieved is a tremendous success. As far as we are concerned we have ensured the rule of law at Northwood Hall.

"The courts have established that most of the payments collected for the heating project were done so unlawfully."

The judge, Mrs Recorder McGrath ordered Mr Maunder Taylor to "make an interim payment to the tenants" of £570,000. This was for 90 per cent of the legal costs of the leaseholders. He was also ordered to pay £75,000 to the first group of leaseholders, led by Mr Whale. Additionally, he was told to pay £15,636.80 to 12 leaseholders in damages as they were not provided with central heating from October 2016.

Another leaseholder celebrating added: "This is a huge victory for leaseholders, at Northwood Hall, yes - but generally, too."

Triplark, the freeholder, released a statement discouraging further legal action and added: "Despite this litigation coming to an end, we along with all other leaseholders are paying for two heating systems at Northwood Hall. Furthermore, we are aware that many other parts of the block require maintenance. We need a manager who is going to be able to drive this project forward."

Initially the plan approved by stakeholders at the 1930s Art Deco block was to use vertical pipework to carry hot water, but an alleged asbestos finding - now known not to be the case - saw then-contractor Parker Bromley decide to switch to a horizontal system of pipes.

The judge, Mrs Recorder McGrath, ruled there should have been a consultation of leaseholders at this stage.

When Mr Maunder-Taylor was appointed as manager in 2016 by a tribunal, he continued with the installation of the new system, and threatened to dismantle the old one - which would have left a number of leaseholders who had refused to have works associated with the new system done in their flats without heating or hot water.

They had already been without the former since September 2016. The judge ruled this was against the terms of their lease and ordered damages to be paid.

Mr Whale is a proponent of an enfranchisement scheme that would see a group led by a "white knight" investor - Lindmead - help leaseholders buy the freehold of Northwood Hall.

But the freeholder has pointed to an independent report suggesting the scheme would leave leaseholders beholden to Lindmead.

A tribunal will again appoint a manager for the building later this year.

Mr Maunder Taylor has not responded to this newspaper's requests for comment.

This article has been amended to clarify that the sum Mr Maunder-Taylor has been ordered to pay was primarily the legal costs of the leaseholders in this case.