That's brilliant Bob, thank you, really helpful and that hadn't shown up when searching. The programming looks straightforward if I can get the right key.
The key doesn't have any markings anywhere inside or out, other than a blurred H144(?) on the transponder.
I did some searching and both Yaris keys on Ebay at the moment are Valeo, so I assume they won't work... and a call to my main dealer says that they now don't sell the transponder circuit board seperately, so its £120 for the key, and I did get a part number of 89070-52081.
My new plan is to visit my local breakers for s