Cheers! Just checked, they were £83.
@sacredhart they're 130bcd dura ace 7800 ht2 cranks. The BB is a sm-bb52. Needs a spacer or two on the drive side between BB shell and BB Cup.
Actually, the drive side crank is a 7800, left crank is a stages PM - 6800.
Frankly, it's a ridiculous bike, but I can't stop dicking about with it 🤷♂️
Edit - I've got a set of 130bcd ultegra ht2 cranks, they're 172.5mm. Had them fitted to the Brompton before I decided to stick the power meter on (which is 175mm). They're a bit scratched and I filed the lips for the little ring down a bit to ensure it didn't foul the Brompton chainstay.