Ok. But from the look of it, I'd need something on the frame for the block to attach to. Right?
I'm on too much of a budget to actually afford a brompton. Guess I should come clean. I bought a 'Tiger' bike off Ebay for less than £100. This is it folded next to my desk (forgive the phone camera quality):
So, not having the front braze ons leaves me with a barbag, or something at the back. Am slowly talking myself into that rear bag. Looking at the price of the Brompton stuff, it doesn't seem like such an extravagance.