Two members of the tri-borough have blamed Hammersmith & Fulham LBC after they ‘reluctantly decided’ to serve notice on ending the arrangement.

Westminster City Council and Kensington & Chelsea RLBC last night said their partner had been ‘appearing to make alternative in-house plans without any formal engagement’.

The two councils said this was ‘causing anxiety to shared staff and potential risks to the joint services for vulnerable people in each borough’ but they added both boroughs remained ‘absolutely determined to continue to work together for the benefit of local people’.

They have now ‘formally agreed to give notice to terminate the shared staffing arrangements’ covering children’s services, adult social care and public health.

Westminster leader, Cllr Nickie Aiken, said: ‘When it was established in 2011 it was quite rightly lauded as an innovation in local authority service delivery.

‘With extremely talented and hardworking staff, its track record speaks for itself with successes in children’s services, school attainment results and youth offending services, to name but a few, combined with £43m of estimated savings.

‘We would not have chosen to end the tri-borough arrangements, which we believe have been a great success.

‘However, both the leader of Kensington & Chelsea and I feel we are unable to continue with tri-borough when we have a partner that we do not believe is committed to it as we are and appears to be making their own plans to leave, without any formal discussions.

‘We can’t have that uncertainty for staff and these vital services, which is why, with much regret, we have very reluctantly taken the decision to terminate the joint arrangements for children’s services, adult social care and public health.

‘We are confident that the future remains stable and positive for the continued sharing of services between Westminster and Kensington & Chelsea, and our door remains firmly open should Hammersmith & Fulham wish to come to discuss a review of the current arrangements and find alternative ways of working together.’

Earlier this month, a well-placed source suggested the announcement of the departure of Hammersmith & Fulham chief executive Nigel Pallace was ‘part of ending the tri-borough’ but this was denied by the council at the time.

Kim Dero, director of delivery at Hammersmith & Fulham is due to take over from Mr Pallace on an interim basis at the end of this month.

When it was launched, London’s tri-borough project was heralded as a ‘highly ambitious programme for shared services with important lessons for other councils’.

Responding to the news, Hammersmith & Fulham Council leader Stephen Cowan said: 'We’ve had concerns for some time about the value of the ‘tri-borough’, its lack of transparency and its built-in conflicts of interest.

'In our last two budgets, Hammersmith & Fulham Council found £31m in savings but the ‘tri-borough’ contributed no more than £200,000 of that, less than 1%.

'Problems with ‘tri-borough’ contracts, procured by Westminster City Council, have cost Hammersmith & Fulham over £5m, including the botched contract for special needs transport that put our disabled children at risk.

'And senior ‘tri-borough’ officers have had to balance Hammersmith & Fulham’s determination to keep Charing Cross Hospital open with Westminster and Kensington and Chelsea’s support for closing it.'

'Triggering withdrawal is evidently a long-planned move by the two councils. I look forward to having sensible discussions with them about how we can all move on in the best way for our residents,' he added.