In reply to LastBoyScout:
I have no idea. I've had them years (literally about 20) and they are not a pair. I think one might be a genuine Vauxhall (from a car we had about 3 cars ago) and one a Halfords.
They have a clamp onto the down-tube, which is too small for the size of the new bikes, and tyre straps which are also too small.
I can kinda-sorta get them to work, but its a real pain, so I was going to upgrade.
Googling led me to the Thule 591, but I'm wondering if I need thule bars for that, which I don't have. Mine are simple bars (about 1"x1")
Rob