Thanks to someone flagging that the site had been hacked, I’ve now restored the site to its original status. The hacking was embedded advertising. Nothing more thank goodness.
It’s a sign of the times, that some person or people can break-in to your website and effectively spray-paint a lovingly-created canvas. This being the web, they get away with it. To me this is a waste of my time both trying to repair the damage these vandals have incurred and trying to find out how they broke in.