Watchdogs have found “significant weaknesses” at the West of England Combined Authority (WECA) in a damning report into the £10,000 unlawful Birthday Bus wrap fiasco.

Last December, the leaders of South Gloucestershire and Bath & North East Somerset Councils agreed with WECA’s top legal and finance officers that Labour metro mayor Dan Norris spent the public money to cover a double-decker with huge photos of him and his dog for political gain.

But despite the politicians saying the bus wrap was “clearly unlawful”, they decided to make no formal finding because former Bristol city mayor Marvin Rees, who was then in charge of the combined authority’s other member council, refused to attend the emergency committee meeting, branding it “improper”.

Mr Norris has denied any wrongdoing and was not given the opportunity to be interviewed by the official carrying out the initial fact-finding investigation into the spending, which was intended to promote the Birthday Bus free travel scheme and tackle a bus driver shortage in spring 2023.

It was pulled by WECA chief executive Richard Ennis, who has since left the organisation, when he found out and it never saw public light of day.

A report to the committee in December said the metro mayor issued a “direct instruction” to staff in his office to spend the government funding on the publicity stunt, a finding he refuted.

Now external auditors Grant Thornton have completed their own probe into the debacle and agreed that the conclusions were reasonable.

In a report to be debated at WECA’s audit committee on Monday, September 9, they found three significant weaknesses in the organisation’s value-for-money arrangements in relation to the bus wrap and issued six key recommendations.

The report said staff in the West of England mayor’s office failed to communicate with senior officers in the wider organisation who were therefore “not sufficiently informed to enable them to intervene” to make sure the bus wrap design complied with government rules.

It said the communication breakdown meant mayor’s office staff were able to “bypass key governance controls that would have prevented the purchase of the Birthday Bus wrap”.

The report said: “In our view, the conclusions set out in the fact-finding report point to the possibility that there was intent on the part of staff within the mayor’s office to deliberately circumvent the governance arrangements of the combined authority to accelerate the Birthday Bus launch.

“It also points to the possibility that there was deliberate action on the part of officers within the mayor’s office to bypass financial controls, specifically through the use of the mayoral office operational budget to fund the purchase, describing the expenditure as printing.

“We have considered further evidence that indicates that the request to raise the purchase order through the proper route had already been stopped, because the senior officers responsible for the programme were not satisfied that the governance requirements had been met.

“However, we accept that the members of the mayor’s office are likely to have acted without a clear understanding that their actions could result in the purchase being deemed unlawful.

“We have significant concerns about the actions of the mayor and the mayor’s office.”

Grant Thornton said the “underlying cultural and behavioural issues” at WECA that led to the Birthday Bus wrap had not yet been addressed.

The auditors said: “We note that the working relationships within the combined authority that contributed to the Birthday Bus issue speak to a culture within the combined authority that has become siloed between the small team referred to as the mayor’s office and the wider combined authority directorate team structure.

“In our view, the actions of the mayor and the mayor’s office in regard to the Birthday Bus wrap issue are symptomatic of a wider problem of division between the mayor and a number of senior managers of the combined authority.

Weca declined to comment further. Mr Norris has been approached for comment.