Originally Posted by FBinNY

The 126mm spindle reflects it's age. Spindles were all longer years ago, and over the years have gotten shorter as the cranksj were offset or bent outward.

I have a bunch of 126mm spindles, but I'm in NYC and mailing costs to the UK would be prohibitive. Search places like ebay-UK, and the dominant mail order firms, for a 126mm bottom bracket. Since the BSC is very common, once you find the right length, it's simply a matter of confirming that it's for BSC/ISO. You may not find this type of BB, and instead can but a cartridge type, but that's OK too.