Can anyone tell me the name and size of the "bit" needed to remove the luggage rails from the floor of the estate boot?

My first thought was a spline bit was needed, but the ones in my local B&Q appear not to have enough ridges, likewise, its not a torx bit as that too does have enough ridges

Not a torx, but often known as spline bits. Unfortunately I can't tell you what size from my head. Make sure you get a long bit / driver though or it won't reach down to them without damaging the rail itself. Guess how I know that!

Oh, and B&Q might be calling them spline bits, but be wrong. I tried to buy some at Halfords and they tried to sell me torx!

The bit you want is a "XZN" or "triple square". As they are almost exclusively used on cars, you should be able to find them in any shop specializing in car tools, that's were you buy them in Sweden anyway.

/Joakim

You would expect so in the UK too. Halfords is supposed to be a car specialist but doesn't even lnow what they are. Ebay or a proper motor factors works for me.