Many thanks to John for managing the server upgrade so professionally as usual (advance info. / website home page notifications etc.).
One tiny piece of info. which I wonder might be of use to anyone :
I usually access the forums by typing the first few letters of the page's URL and selecting the full URL from the dropdown list which I then see, to obtain the page.
Whereas the Forums' index page's URL used to be
http://www.signalbox.org/forum/index.php ,
it now seems to be
http://forum.signalbox.org/ .
Accessing the Forums' index page via 'the blower' symbol on the main website Homepage finds it anyway, no problem.
Thanks again John.