Just in case anyone is under any illusion. This is a direct lift from the Intellectual property office website.
Infringement
What is trade mark infringement?
If you use an identical or similar trade mark for identical or similar goods and services to a registered trade mark - you may be infringing the registered mark if your use creates a likelihood of confusion on the part of the public. This includes the case where because of the similarities between the marks the public are led to the mistaken belief that the trade marks, although different, identify the goods or services of one and the same trader.
Where the registered mark has a significant reputation, infringement may also arise from the use of the same or a similar mark which, although not causing confusion, damages or takes unfair advantage of the reputation of the registered mark. This can occasionally arise from the use of the same or similar mark for goods or services which are dissimilar to those covered by the registration of the registered mark.