A deal that would see nuclear staff take over large parts of Copeland council’s headquarters has taken a huge step forward after three years of talks.

Sellafield workers already occupy space on the ground and first floors of the Copeland Centre, which was built as part of a Private Finance Initiative arrangement dating from 2004.

But the outline of a new lease voted through by council chiefs would see Sellafield Ltd occupy all three floors of the building on Catherine Street.

A meeting of the borough council’s executive heard that the negotiations had been hampered by the PFI arrangement but were now moving towards a resolution.

Councillor David Moore, executive portfolio holder for nuclear and corporate services, said: “When I picked up this portfolio I was told ‘It’s all right, Sellafield is going to be coming in’. Nothing could have been further from the truth.

“We had a willing tenant in Sellafield wishing to move in, but the obstacles have been absolutely unbelievable and the negotiations very protracted.

“It was long thought that a deal had been done early on and Sellafield were going to take a lease on this building – that was pretty much done and dusted.

“What actually transpired is there had been some conversations. But nothing had been firmed up and, certainly, there had been no discussions with Equitix who currently own the building.

“We have tried to work through that and have come up against numbers of obstacles, mainly with the owners of the building. It’s a PFI building and that’s led to one issue after another.

The 25-year agreement made under a former administration has annual repayments of £1.6m.

Under the PFI, private investors build, finance and manage infrastructure projects which are then leased by the state.

As part of the deal with Sellafield, the council would provide 50 on-site parking spaces for Sellafield workers as well as a further 80 parking spaces in a proposed new car park at the former Ginns depot site.

The executive approved the proposal to enter into the lease, with draft heads of terms already agreed.

Council chiefs also voted to delegate approval of any minor changes to the terms of the lease, following agreement from Sellafield, to the chief executive, the council’s solicitor, a section 151 officer and the portfolio holder.

The council will continue to operate from the ground floor of the Copeland Centre.