Ok, having had nightmares with my trainers and feet for the last month-ish, I've done a quick test this morning - wet feet, stepped onto a bit of card one for each foot...and the results are in!
My left foot looks pretty neutral, so no problems there, bar anything caused by my current trainers.
My right foot is low-arched, under-pronation, which was the reason I got my current trainers, because my right leg was having shin splints.
So..... which type of trainer do I go for to support my right without damaging my left!