Seems that i was incorrect in saying that the Conti 3 is a directional tyre, it just states on the sidewall "outside" with NO arrows, so that's not now a problem.
So my solution is to obtain a 19" alloy from Peugeot (or a cheaper alternative from a large wheel retailer) & get it fitted with a new Conti 3, again from a discount retailer.
I realise that to fit it in the boot well it'll need deflating, but for my purposes & being 100% legal it's worth it, if only for peace of mind !
Cheers to all that replied to my post. Everyone will see this problem in different way, the way that suits them !
Mike.