Brompton quick release

So, I bought a clip for the rear triangle of my ancient Brompton so it doesn't fold under when lifting the bike. Got home, cant fit it as it requires a 6mm quick release. My Brompton has a thicker QR.
My question is do I have to buy a Brompton one (they are a tad expensive) or can I just buy a cheap QR like this one
http://www.ebay.co.uk/itm/VAVERT-QR-QUICK-RELEASE-SEATPOST-CLAMP-6MM-BOLT-FITTING-/331071269594?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item4d1562aada
so I can fit this clip.

Your thoughts are appreciated.

I've tried using a standard seatpost QR, but frankly, you're better spending the money for the pukka Brompton part. It stays in line instead of hanging down, and the cam action is just right, whereas a standard QR goes from too tight to too loose without ever being perfect.

The brompton design is perfect and should not be changed. This rear traingle clip is heresy and should be burned. Should you continue on this path then true brompton riders with pure bromptons and 100% brompton approved accessories will hiss as you pass.

Apart from that, I'm guessing you got one of these?

http://brilliantbikes.co.uk/brompton-folding-detail/340-brompton-rear-frame-clip-retrokit-5053099040179.html

Have a measure of how long that square section is and make sure the clamp will be wide enough. The brompton ones have notches in them so it won't spin around, if you want you can notch the black plastic bit on the one you linked but it's not the end of the world.

That kit has the new QR included, or you can get it on its own

http://brilliantbikes.co.uk/brompton-folding-detail/453-brompton-seat-pst-clamp-quick-release-5053099040186.html

I already have the clip kit, didn't figure on the qr issue. £18 for a quick release! Anyone got a 6mm brompton qr for sellz?