The witnesses
7.Each side had one expert witness who was cross-examined. There was also a witness statement from Paul Fennell, Chairman of Marflow, who was not cross-examined. 8.Marflow’s expert was Eric Mace. Mr Mace became an apprentice plumber in 1956 and has since worked in that trade for several employers. For a while he ran his own plumbing business. In 1996 he became a part-time professional standards inspector for the Institute of Plumbing although he also continued to trade on his own account, latterly as a consultant. Mr Mace is a former President of the Chartered Institute of Plumbing and Heating Engineers. I found Mr Mace to be a careful and it seemed to me reliable witness. 9.Stephen Walsh was the expert for Cassellie. He began as an apprentice plumber in 1964 and became a Chartered Engineer in 1983. He was first instructed as an expert witness in 1984 and his curriculum vitae gives the impression that being an expert witness is largely what he has done since. In cross-examination he said that he has been instructed as an expert on more than a thousand occasions. A small number of these were patent cases although none went to trial. 10.Mr Walsh gave evidence on the common general knowledge without having taken on board what that is. It emerged in cross-examination that his idea of the common general knowledge was any information made available by the Patent’s filing date. He said that he had carried out weeks of research in his own extensive library and had called colleagues in the industry and manufacturers to find out whether they had anything that could assist him in his search for the common general knowledge relevant to this case. 11.There were two cited items of prior art. Unusually for an alleged infringer’s expert, Mr Walsh said in his report that the Patent disclosed an inventive step over both. During an examination-in-chief he obligingly disclaimed a section of his report which included his statement that there was an inventive step over one of the items of prior art. Later, in cross-examination, he went back on that. I sometimes found Mr Walsh to be unclear in what he was saying, and I am not convinced that he was always sure either. Mr Walsh was not a satisfactory witness.