[Geoff Bacon]

Thanks for the advice Mike.

Although all the files were still in place, I opted to do a full restore via the companion.
Very easy and quick.
It all looks ok 

I was lucky this time because I don't normally backup the database; I only backed up because I was upgrading MSP. 
Moral: Back up the database whenever it contains changes you don't want to lose!

Cheers
Geoff