Plans for two Suffolk councils to significantly downsize their office space will proceed as planned after a challenge around the finances behind the decision was quashed.

Babergh and Mid Suffolk district councils' cabinets agreed to trigger a five-year break clause in their contract for office space at Endeavour House in Ipswich, which will see them reconfigure their space and hand back one of their two floorplates.

That is to enable hybrid working arrangements to continue that will see staff working part of the week from home and partly from the office.

Six Babergh councillors challenged the cabinet decision, saying that the short term costs of £250,000 for each council had not been significantly considered at Babergh's cabinet meeting, and the report did not contain a detailed enough breakdown of costs.

The six said that as the decision related to expenditure of more than £150,000 it was considered a key decision and the opportunity to debate and decide on the full costs should be available.

The challenge, known as a 'call-in', was heard at a special meeting of the council's scrutiny committee where councillors upheld the cabinet's original decision and were satisfied costs had been considered.

It means the break clause will be triggered next month and changes made to hand back one of the floorplates later this year.

Councillor David Busby, cabinet member for assets and investments, said: "Detailed costs will not be available until the full technical design has been completed and the works tendered, but even with costs rising we anticipate coming in under budget".

He added: "Given the fact this project has been ongoing for nine months or so and there has been working groups and feedback to the cabinet and to all council members, we fed back the information that we had which was the best estimate of the costs from consultants who know the building, having been occupied in the building themselves."

Senior finance and monitoring officers did not raise any concerns over how the decision had been reached.

Published figures indicate each council would face costs of £250,000 but savings of £338,000 would be delivered, and create a more fit-for-purpose working space for the councils.

Councillor Melanie Barrett, who was one of the six to call-in the decision, said the decision "cannot be seen to be made on such a ballpark figure" and explained that it was "not clear if the landlord had been approached to shoulder some of those costs".

Cllr Barrett added: "We understand building costs are expensive – that doesn't mean we shouldn't analyse and make informed decisions about that with more information on what the cost is, precisely because it's a lot of money."

The two councils moved out of their district offices in Hadleigh and Needham Market in 2017 to unite their shared workforce under one roof and save costs.

Some councillors questioned the decision amid fears it would move the authorities out of the districts they served. The latest report said that a return to their districts was not currently viable.