Hallamshire had entered into a building contract with the local authority, South Holland District Council. It incorporated the JCT Form of Building Contract 1980 Edition Local Authority's version. They agreed that phase two of the project, in respect of fit-out works, would be dealt with by means of a variation instructed by the architect. The instruction provided that the new work would be carried out in accordance with the existing contract and that the prices would be agreed at "fair and reasonable costs" by the quantity surveyor. A dispute arose over the amount to be paid to Hallamshire, which was referred to arbitration.
The arbitrator decided that the instruction had contractual effects. The revised scope of work and the price or mechanism for agreeing the price had been agreed by the parties. It had been accepted during the course of their negotiations and in part by their conduct. Hallamshire challenged that finding on the basis that the instruction merely established a tendering process for agreeing the prices, and secondly, the agreement to "fair and reasonable costs" by the quantity surveyor meant that the parties had not agreed those prices for the work at the outset of phase two and so the arbitrator had erred in law.