It comes as one of the executives claimed the group misused “draft” figures to inflate the value of its hotels.
In the last six years Gavin Woodhouse has raised more than £80m from amateur investors to build care homes and to acquire and refurbish hotels.
But many of his projects are incomplete and at least £15m appears to be missing from his firms’ accounts.
Peter Moore, who helped launch Center Parcs in the UK and was Northern Powerhouse Development’s (NPD) non-executive chairman of leisure, was fronting the delivery of Woodhouse’s £200m in south Wales, which is being endorsed by .
In a statement, Moore said: "It is with great regret I have to announce that I resigned last week from NPD, because recent allegations are causing understandable concern to many of the organisations involved in delivering the Afan Valley Project.
"This has resulted in my no longer being able to focus on the complex task I came on board to do", he added.
Russell Kett, the chairman of the London office of the hospitality consultancy HVS, was a special advisor to the board of NPD.
Mr Kett resigned after claiming that NPD used "draft" figures that HVS had provided in order to increase the value of its assets by £22m in its annual accounts.
Mr Kett said he is "embarrassed" and "concerned [his] professional integrity - and that of HVS - is being called into question” by NPD’s financial reporting.
"I have therefore decided to terminate my relationship with NPD and to withdraw from my role as an advisor to the company."
In February, HVS carried out the revaluations of nine hotels owned by NPD.
According to NPD, the valuations showed that the Fishguard Bay hotel which was purchased for £966,720 in June 2017 is now worth £6.7 million - despite the property never undergoing any renovation work.
Northern Powerhouse Development (Holdings) - the company which operates the Afan Valley project and a group of 11 hotels - posted a pre-tax profit of £7m in the year to March 2018 and said its balance sheet had net assets of £11.2m.
The company would have been heavily loss-making and balance sheet insolvent without the upward revaluation of the hotels by £22m.
The accounts, which were personally signed off by Gavin Woodhouse, state "all hotels have been independently valued by HVS Global Hospitality Services".
However, in a statement issued to ITV News and the Guardian, Russell Kett said the valuations were incomplete and that NPD used them without his knowledge or consent.
Mr Kett added: "In February 2018 the valuation division of HVS London issued a draft report on nine of NPD’s hotels for their internal asset evaluation purposes only and to assist in their strategy initiatives; this was subject to a number of specific assumptions."
"A final version of this draft report was never issued because of outstanding information relevant to the valuation conclusions.
"As we were effectively waiting for crucial information to assist our valuations (relating to the extent and cost of capital expenditure), any figures used in any professional capacity cannot be endorsed by HVS."
A spokesman’s fro NPD said: "We engaged HVS to produce independent valuations of our properties. We strenuously deny any wrongdoing".
"We regret that Peter Moore has resigned from Northern Powerhouse Developments.
"Peter played an important role in NPD’s Afan Valley adventure resort project.
"We can assure all concerned that we remain as committed as ever to delivering the Afan Valley project in Wales as planned."
Williamson & Croft, Woodhouse’s accountants, did not comment.
Gavin Woodhouse has come under increasing pressure since the publication of last week’s undercover investigation.
In response to the investigation the Bear Grylls Survival Academy says it is "conducting a full internal review of the relationship".
A hearing is scheduled for Thursday.