Cornish-based manufacturer Devoran Joinery supplied the windows and doors to Mr Perkins' new house in Hertfordshire. The joinery was badly made - so badly that two contractors refused to install it. When it was eventually fitted, there were still faults. The casements on the upper floor were too small for the frame, lead strips were oxidising, and the utility room door leaked. The bay window to the master bedroom was too small for the brick opening and tape had to be applied all round to reduce the draught.

Not surprisingly, Perkins did not pay Devoran in full arguing that the cost of putting things right was greater than the sum he owed. Devoran sued for £11,370.56 plus VAT.

The case had two experts. One, Mr Keyworth, for Devoran, was an architect, experienced in joinery but not in costing. The other, Mr Bussey, for Perkins, was a QS. In court, Keyworth admitted that his proposed method would not work completely, that his assumed hourly rate of £10 could be low and that he had not included access scaffolding.

Even so, the judge preferred Keyworth's evidence, saying he was "older and more experienced" and awarded £6,100 for repair costs, less than half of what Bussey had estimated. Perkins was not happy and he appealed. The Court of Appeal decided that the matter had to be re-tried (at even greater legal expense) to discover the true cost of effecting the proper repairs.

Moral: "Experts" aren't always expert

Case: Devoran Joinery Company Limited versus Perkins. Court of Appeal (Civil Division) July 30 2003