I did do a regular backup. Problem was - I corrupted the latest backup while trying to update it. Only option I had then was to go back to a 12-month old backup. Long story but I'm definitely gonna make more images.
I got the server back online in a few hours but it's taken me until now to get it reconfigured and updates applied etc.
Good news though... we're back running on the master server 100% now!
Thanks for all your patience!
I'll have my easter weekend next week i think lol