Thanks guys – sorry about the delay.
Managed to reload a backup and get running but still getting strange problems.
Trying the front-end via Pingdom, gtmetrix etc gives load times circa 2 seconds yet when working in the back-end I’m looking at speeds of 30 seconds or so to change any pages in the admin console.
The site went off this morning with a 502 error for about an hour before it came back on (I use cloudfare as a CDN) but the hosts are insistent they can’t see any issues in the logs or with the server load that could explain it.
Craig