I have finally managed to trace the error which was causing the problem with the website. It was being caused by some coding in a plugin. The developers of the plugin will have to fix it before the problem before I can use it again. This will, unfortunately, cause some problems with the back-end of the site.
I believe the problems relating to the back-end will have no bearing to the experience of any user. Pending the developers fixing the plugin I am looking at the possibility of finding an alternative plugin which will replace its functionality.
If anyone experiences any problems using or viewing the site, please let me know.