10 February 1998. The plaintiff engaged the Multi Group for the design and construction of a warehouse complex by the contract in writing dated 10 April 1989. The contract was an amended JCT 81 design and build contract. Multi Design Consultants LTd was a member of the Nulti-Group responsible for the design. However, it also did design work independently on works not constructed by members of the group, and conversely the latter constructed works not designed by MDC. MDC left the Multi-Group by way oa a `management buyout` in April 1991. MCL became insolvent and was dissolved in February 1996. Davis Langdon and Everest were the plaintiff`s quantity surveyors as well as the employers representative under a separate contract. The roof, as laid, was defective in that the `end lap` joints were not watertight, causing substantial leakage. The plaintiff commenced litigation against both MDC and DLE. The plaintiff claimed that a collateral contract existed with MDC, and that MDC warranted