Mr Laing, who is a member of the John Laing construction family, most recently failed to convince London Zoo - a former prospective partner - that a similar aquarium project on the site of the Mappin Terraces could generate enough profit to service the pounds 32m financing cost.
Officials at the zoo, which rejected proposals from NZD 10 days ago, have accused it of a confrontational negotiating manner, vagueness and failure to come up with a convincing business plan.
NZD announced last week that it had recruited Sir David Attenborough, the TV naturalist, as a director and had begun talks with the Natural History Museum instead. Advised by Samuel Montagu, the merchant bank, it plans to build an aquarium on the 14-acre museum site in South Kensington to house creatures from sharks to jellyfish. There would also be a movie theatre using high-resolution IMAX technology.
The talks with NZD have been sanctioned by Peter Brooke, Secretary of State at the Department of National Heritage, which gave the museum a grant of pounds 28.9m last year.
Mr Laing, while admitting to mixed business success in the past, is convinced he will be able to raise the necessary cash and insists that the NZD board has the relevant expertise.
However, John Edwards, a solicitor and council member of the Zoological Society of London (ZSL), which owns London Zoo, is more sceptical. 'I didn't really think they had a viable project,' he said of the Mappin Terraces plan.
'We could not see that we would get enough money to justify the arrangement. Ultimately, it was the vagueness of the thing - we asked for figures, and the figures were simply not forthcoming. One excuse they gave us was that their bankers were on holiday.'
NZD has no track record. According to documents at Companies House, it is an off- the-shelf company, Bidgate Ltd, renamed in April 1992 and controlled by Mr Laing, who owns 198 of the 298 shares.
Mr Edwards' view is echoed by other sources close to London Zoo. One told the Independent on Sunday: 'At every meeting they kept on wheeling in Peter Chermayeff' - an American architect with experience of building aquaria and an infectious enthusiasm for the subject. 'Even at the very last meeting, we were still getting Chermayeff, not spreadsheets.'
The source described the negotiating tactics of Ronnie Harris, Mr Laing's number two, as 'combative and confrontational'. At one stage, relations descended into a furious row when NZD held a press reception at the House of Commons without warning the zoo, which had been planning its own press conference. There was also an acrimonious dispute over an alleged salt-water lake said to have formed under the Mappin Terraces.
Mr Harris, who describes himself as having worked in consultancy for 20 years, is a director of NZD. His other directorships include the Museum of the Thames Traitors Gate Ltd.
Meetings became strained when zoo officials were refused any breakdown of the likely costs of the project or details of how the debt would be serviced.
Dr Jo Gipps, director of the zoo, would only say: 'Discussions were long and businesslike but never reached the point where the board felt comfortable with the physical plans or the financial predictions.'
It is understood that Charles Perrin, deputy chairman of Hambros Bank and a former ZSL council member, analysed an earlier pounds 61m proposal of NZD to take over the running of London Zoo and voiced misgivings about the ability of the venture to service its debt. The proposal was rejected in September 1992.
Earlier, a pounds 55m proposal for the zoo by the Regent's Park Zoo company, of which Mr Laing was a director, collapsed when its managing director, Dorion Brisbois, resigned.
Other proposed business ventures with which Mr Laing was connected have failed to be realised. In 1991, Bristol City Council pulled out of a scheme to develop Redcliffe Caves in conjunction with the Heritage Group, of which Mr Laing was chairman, after years of financial wrangling.
An NZD plan to revive Kilverstone Country Park in Norfolk with animals from Windsor Safari Park failed in February this year when Cork Gully, the receivers to Windsor, placed the animals elsewhere.
Mr Laing insisted the equity and loan finance would be forthcoming for the new project. 'We collectively feel that if we can find the right location with proven visitor flows, we can prove to the banks that it will support a major investment.'
He said John Laing was committed to providing pounds 3m to pounds 4m of the equity in the zoo venture. 'On the new project, Laing's will be capable of taking a position. McAlpines (another construction firm) are interested.'
Mr Laing puts his own net personal worth at pounds 1.25m, after taking account of all liabilities. Investments in family trusts come to 10 times that figure. He said he had personally committed pounds 500,000 to the aquarium plans, half of it now spent. He is a director of Eskmuir, the family property business.
Daiwa Europe, the Japan- based bank, had some potential Far Eastern investors lined up for the zoo venture. It said last week it was still interested in the new project.
Sponsorship, according to Mr Laing, would have contributed pounds 8- pounds 15m to the zoo project. Although mentioning several blue-chip companies, on Thursday he could not name any sponsors who had been fully committed to the project.
John Sleeman, director of Samuel Montagu, said the debt finance - probably 60 per cent of the total cost - would be forthcoming for the new project: 'We've sounded the market out. For the right deal, it is do-able.'
Mr Harris said the reason the zoo proposal failed was that the ZSL council could not agree among themselves. 'We kept back the full financial figures because we believed they were at war with each other on the council.' The Redcliffe project fell through because Security Pacific, the American bank financing it, pulled out at the last moment, he said.
Mr Laing, who is himself a fellow of the ZSL, admitted the relationship with the zoo was 'very difficult' and that 'funding remained an issue', but the main reason for the breakdown in talks was that the zoo would not give up sovereignty.
A qualified architect and vice president of St John's Ambulance, he points to his company Health and Racquets Club (Europe), which owns the St Albans Health and Racquet Club, as evidence of his business success.
Jane Bevan, a museum spokeswoman, said of NZD: 'They approached us. We know nothing of the detail of the negotiations with London Zoo.'