Hi Guys,
Thanks for your comments.
Got lucky yesterday, David, TSSC member 1969Mk3Spitfire, went to the Classic Car Show at Tatton and saw a pair of Mk3 seats for sale and texted me to let me know. I was there an hour later and purchased them for £160. The driver's needs recovering as it has a couple of tears but the passenger looks very good. Unfortunately they did not have the runners so I am still on the lookout for a driver's side one. At a pinch the passenger side one can be used temporarily but to get it in the adjuster handle has to be moved up hence unlocking it. But as it is only a mile to the trimmers it should not be a problem.
Thanks again David, 1969Mk3Spitfire.
Cheers.