[2007] EWCA Civ 663, 4 July 2007. Examines what can happen when a contract does not contain a provision permitting it to be varied. Respondent subcontractor (S) had entered into a subcontract with appellant contractor (P) to undertake electrical works on the basis of a very simple contract which had no contractual terms or conditions identified. This meant that any necessary terms would have to be implied. P was subsequently required to do more work under the main contract which meant S was required to do less electrical work. P sought a reduction in the amount payable to S, claiming the subcontract was a unit price contract, but the judge held that the subcontracts were fixed price contracts and that P was not entitled to any reduction. P then argued that terms should be implied into the subcontract dealing with variations and further relied upon the doctrine of substantial performance. "Held": appeal dismissed. The fixed price contract did not contain a provision permitting it to be varied, and therefore although S had not undertaken the full extent of the works, P was still liable to pay the full subcontract sum.