There appears to be some pattern parts with the new valve on ebay, for Ka, Fiesta, Focus etc, so I guess futher enquiries would turn up one for a Puma.
One was priced at £25+, another at £70+.
Don't want to make you cry, but mine came from ebay, it's a Valeo/LUK (who make for Ford), and in true "yippeekiay" tradition, got it for £13.25, delivered!