A number of applicants file similar patent applications at both the Intellectual Property Office (IPO) and the European Patent Office (EPO). In cases where both applications result in granted patents valid in the UK, the IPO carries out a check to determine whether there is a conflict, that is whether both applications relate to the same invention. It will revoke a GB patent if an EP patent for the same invention is granted designating the UK. Over the past nine years, 1,148 GB patents were considered by the IPO for revocation in these circumstances (the data for the tenth year are not available). Many applicants amend one or other to remove any conflict, therefore avoiding revocation. There are over 500 cases where an application has been granted by one office and not the other, which is well below 1 per cent. of the total number of patents granted by the two offices. In many cases these applications are still pending before the other office. Determining precisely the outcome of the remainder, many of which will have been withdrawn for the applicant’s own reasons, would involve information which is not held centrally and which could be provided only at disproportionate cost.