Tropus chairman David Hudson defended the study, released to the House of Commons last week, by pointing out that it was backed by a separate study by consultant David James.
Tropus' contract with client Wembley National Stadium Limited was not renewed after it expired in 2001. WNSL last week said Tropus was a "disenfranchised consultant" when it wrote the report; this week it said it was "much happier" with Symonds, the firm that replaced Tropus in March.
Hudson said: "To say we were a disenfranchised consultant is just not the case – our position was no different from anybody else's on the consultant team when we wrote the report. We were engaged for four years on the scheme and there were never any questions raised about our performance."
He said the report, given to the Football Association last August, had been endorsed by James. He said: "Our report was backed by the James report – in fact that report went further in terms of detail."
Hudson added that Tropus had no intention of scuppering the construction of the stadium. He said: "We do not want to screw up the prospects of building a new stadium. It's going to be a magnificent product. I would like to see it built. What we are upset about is we were attempting to do a professional job but were prevented from doing so."
The Tropus report and the James study, also published last week, both lambasted WNSL's failure to procure and manage the project properly. They centre on two crucial periods: the lead-up to the appointment of the Bovis/Multiplex consortium as preferred contractor on 18 February 2000, and the subsequent dismissal of the joint venture partnership on 30 August after the appointment of Multiplex on 1 September.
Both reports conclude that WNSL did not adhere to best practice, leading to doubts over the fairness of the procurement process and the achievement of best value.
The James report, which raised concerns over potential conflicts of interest at WNSL, concluded: "The process adopted by WNSL is unlikely to satisfy best practice standards as usually deemed necessary in any project involving government or lottery funding."
What we are upset about is that we were prevented from doing a professional job
Tropus chairman David Hudson
The Tropus report said the £326.5m contract signed by WNSL with Multiplex on 1 September 2000 had been agreed with undue speed.
It said: "In our professional experience we find it remarkable that this two-and-a-half page letter (with five pages of attachments) was signed on behalf of WNSL without appropriate legal advice being taken."
The report added that Multiplex could claim £12.6m against WNSL if the contract was terminated.
Tropus claimed that the cost of the contract rose from £326.5m to £360m and was heading above £400m by August of last year. Its report concluded: "Tropus did not consider in August last year that the Multiplex construction cost offer had been properly interrogated."
Tropus claimed that the scheme could have been resubmitted for tender as late as last summer. Hudson said: "UK and large European contractors would still have been interested in the project. If they had started the process in the summer, demolition could have started at the end of last year. This scheme was capable of being built by a UK contractor. The UK industry was not given a legitimate opportunity to pitch for the scheme."
Both WNSL and Multiplex insisted this week that they were focused on the future rather than the history of the project.
A Multiplex source said: "There has been a lot said about the history of this scheme. All the effort right now is to get the deal done."
Lest we forget: The long and weary road to Wembley II14 July 1999
WNSL asks contractors to submit bids for Wembley stadium. Mowlem, HBG, Sir Robert McAlpine and Bovis/Multiplex are among those that respond.
18 February 2000
Bovis/Multiplex are appointed preferred contractor, despite putting forward a non-compliant bid. No evidence of other bids being lodged by either Mowlem or Sir Robert McAlpine.
30 August 2000
Bovis/Multiplex are dismissed as preferred contractor after putting a £340m pricetag on the scheme.
Multiplex is appointed preferred contractor on a guaranteed maximum price of £326.5m (which excludes design fees) with a 39-month programme to build the stadium.
11 January 2002
WNSL reveals that it is shaking up its management team. WS Atkins’ Michael Jeffries later made chairman.
21 May 2002
Tropus and David James reports are published. They raise concerns over WNSL management and procurement.