Well, after a few messages to and fro this afternoon I have now got the Gazetteer back as it was so for anyone wishing to get this useful site back, here is the copy of the last email:
Dear Gillian,
It sounds like you need to clear your browser cache. See:
https://support.mozilla.org/en-US/kb/how-clear-firefox-cache
It seems that a particular quirk of Firefox is that it does not easily forget things.
https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings?redirectlocale=en-US&redirectslug=reset-firefox-easily-fix-most-problems has some instructions for ‘refreshing Firefox’, but I am not an expert on the Firefox browser!
You may also view the gazetteer at abcounties.com/gazetteer.
Regards,
Michael
I haven't tried clearing the cache, that is a task for later, but I opened the page by using abcounties.com/gazetteer.