This issues has now been resolved.

We are experiencing problems with our site search and are working to resolve them as soon as possible. We are aware of the issue, so there is no need to contact web support to report this problem.

In the meantime, if you are experiencing any issues with the site search, we recommend that you use an external search engine such as Google if you need to look for information on our website.

We will provide further updates as soon as possible, and apologise for any inconvenience caused.