We're back from Edinburgh and had a bit of fun with British Midland on the way up.
They "lost" our car seat in transit from London and so we complained. I filled out the lost luggage forms and mentioned that we were concerned about how we were going to get Lauren to Maggie and Peter's house.
The girl smiled and pulled out a car seat for us (brand new - still in it's packaging). I told her thanks and asked if we just drop it off on our return leg or give it to the courier who would deliver our lost luggage the next day? She told us that car seat regulations were such that it couldn't be reused, so we could keep it!
That means we have been able to leave one with Maggie and Peter so we don't need to lug it up to Edinburgh again!