Baldock Classic Car Show is on again this Sunday, 20 May. It takes place in the High Street and Market Place and is usually well supported:
http://www.baldockfestival.org/wp/event/baldock-classic-car-show/
Bought them from Rimmer, part number RR1370, cost £23.33 + Vat in September 2016. Made several attempts to stop the rack slipping before going for one solid and one rubber mounting which appears to have cured the problem.
My solid mounts allowed the rack to slide particularly when using a hard lock at slow speeds to pull away from a kerb. Now have one solid mount and one rubber mount - a tip I read somewhere (maybe on here) and that has solved the rack movement problem.
I fitted a lowering block and longer studs from Canleys when the new rear spring on my GT6 Mk3 sat too high. Had to re-thread the new studs as the threads were too short to clamp the GT6 spring.
I had exactly the same problem when I first got my GT6. When closing the fuel flap the rubber seal was not pressing tightly against the petrol inlet pipe. I have improvised a spacer behind the seal as a temporary fix until I can work out a permanent solution.
Not sure if there is a cheaper way than paying for a "Heritage" certificate - but I am sure some one else will know.
https://www.britishmotormuseum.co.uk/archive/heritage-certificates