The amounts were actually a few orders more than what I said, so you can imagine my sweaty handpalms!
Much thanks for the help. The forum quality compensates for the complications in working with Multibit wallets, backups etc. I thought that maybe 'change' of earlier spends had come back on different 'keys' and were lost due to not updating the wallet backups before changing from 8.1 preview to windows 8.1. Or something like that.
It is the cost of not completely understanding how everything works in detail, even though I am definitely not new to it.
I need a beer! Thanks guys!
Glad to hear that.
Enjoy your beer and bitcoin