CA 23 November 1989. The plaintiff (W) a carpenter was engaged by the main contractor (R) in the refurbishment of 27 flats. The subcontract was dated 21 January 1986 and included an implied term for interim payments relating to the amount of work done. By March W was in financial difficulties because the agreed price was too low at £20,000 and his failure to supervise his workmen adequately. In April B agreed to pay £10,300 in addition to the original £20,000 (£16,200 of which had been paid in interim payments). W continued work until May 1986 when other carpenters were employed to complete the work. W brought an action for unpaid sums. B claimed that neither the balance of the £20,000 nor the extra £10,300 were payable until completion and as the work was not finished no further sum was due. The case held in favour of W on the grounds that the extra £10,300, at the rate of £575 per flat was an oral agreement varying the original sub-contract. By May eight flats had been substantiall