To try and ensure the site continues to function properly and simplify site maintenance only a few essential links to external sites have been included. We do not intend to reduce the usability of the site in order to publicise other web sites. If you do find a broken link on this site please let us know so that it can be repaired. Deep-linking directly to another site's pages, which increases our maintenance burden, and bypasses the remote site's navigation, security, or counters, is not a strategy we consider. We have not found a practical reason to use elements of Shockwave, Flash, Realplayer, scrolling text, marquees, popup windows and so on. Together with your browser and email software, the only programme you may require to use the site is a portable document (.pdf) reader. You can download the latest Acrobat version from Adobe by selecting the link on this page, but you may prefer an alternative. We have used this cross-platform format to preserve the integrity of our documents, and to protect you from receiving malicious code.