Thanks all for your compliments. You see, I'm a Yorkshire chap so I look for simple cheap solutions............

But funnily enough, the family tree goes back to Herefordshire about 1800. Not that far from Malvern.

I'd go for a single plate, I think one each side might rotate unless it's shaped to fit inside the box. Worth experimenting. You're right about stainless. It's a pig to work with.