CA 12 May 1992. The appellants M entered into a building contract with a construction company, R, under JCT 1980. To avoid liability for VAT, which was being introduced, M arranged to pay £4.5m of the contract price of £5.5m in advance. To secure the risk that R might fail to complete, M obtained an advance payment bond from the respondents N. In April 1990 R went into receivership having only done work to the vaue of £1.1m. M therefore made a claim on the bond. N contended that their liability had been discharged. The contract, entered into after the bond, had provided that M give possession of the site in mid-May or within six weeks. In fact possession was not given until 24 July. At the initial hearing it was held that the bond constituted a contract of guarantee, that the terms of the contract were incorporated into the bond and that the surety was discharged by a variation of that contract. M appealed however the decision was upheld.