This may help with finding out what size your arb bushes are.
In the service book at the front is a sticker with the paint code etc, on that is a list of three digit codes one of them codes will match one of these
OAE is the 23mm bar
OAL is the 21 mm bar
I think the sticker in the front of the service book is the same as the one in the boot for all those of you that don't have a service book.
Hope this helps, and cheers to Patch for pointing me in the right direction