Hi Gareth,
I can see where you're coming from with regards to asking for the part number, but it reduces my time in asking lots of questions. Most of the ones I'm being offered are from 2013 onwards which will not fit, this is even after giving them the plate number. Due to my location getting items here is pretty expensive at the best of times, I was quoted £600 for a new frame, which is totally unrealistic for a car this age. Second hand route will do for now, if I don't find one, I will look at your suggestion and pass the info onto my mechanic.