An allegation of bias against CABE's design review committee has sparked a DCMS audit into conflict of interest issues at the commission.
The examination will seek to establish whether CABE operates within the Nolan principles, established to eradicate sleaze in public life.
Its primary focus will be Stuart Lipton and any potential conflict of interest that exists between his roles as chairman of CABE and of Stanhope - one of the UK's largest developers.
The audit, announced on Monday, will be led by chartered accountants AHL and any findings or recommendations for change are expected within the next couple of weeks.
The review is the government's response to a complaint from a member of the public against CABE's treatment of two schemes at South Kensington and Croydon Gateway.
The complainant, understood to be a member of the South Kensington Underground Development Action Group, has alleged a connection between the design review committee's treatment of Terry Farrell's proposal for South Kensington Underground Station and Lipton's role as the scheme's developer.
CABE's handling of two competing schemes for Croydon Gateway is also understood to be a source of complaint. A scheme by Foster and Partners for Stanhope is doing battle with another by Michael Aukett for developer Arrowcroft.
CABE's director of communications, Matt Bell, however, said the commission was confident its proceedures to protect against conflicts of interest were sufficiently 'robust'.
'We have full guidance to deal with potential conflicts of interest, ' he said. 'We take issues of public probity seriously. It is important things are transparent. If the audit helps to do that, then great.'
However, he acknowledged that the need to attract high-calibre experts to the commission could raise the potential for conflicts of interest. And he admitted that as many as half of all commissioners could have some form of connection to Stanhope.
These include Ken Shuttleworth, who is currently working for the firm, Sunand Prasad, whose practice Penoyre & Prasad has worked on Stanhope's Stratford Project, and Paul Morrell through his position at Davis Langdon & Everest, which acts as an adviser to the developer.
However, Shuttleworth said there was no reason to be concerned about the commissioners' business connections. 'There is no bias towards Stanhope schemes at the design review, ' he said. 'In fact I think it's the opposite. They probably have a harder ride.'