Had a front spring snap the other day just as I was pulling away. So I looked under the rear seat for the code, it was QK(REB000890). Took a chance on some FAI springs part number SP155 and I'm happy to report that they are a good match.
Same length and feel like the same stiffness. Not to bad for £63 the pair.
http://www.ebay.co.uk/itm/Coil-Sprin...EAAOSwPCVX2s~d