As promised I am reporting back.
I experimented on a night when there was just me and and Tony home. After I had cooked our meal and had turned off the oven I then put a couple of the merengues onto a metal baking tray and left them in the 'cooling' oven while we ate. It DOES work!! They crisped up just fine and should one be caught out as I was, it is a tip worth remembering. I am not saying I would make a habit of it but I really don't think anyone would have known the difference ( apart from you all who I shared this with
) I would only add before signing off to say watch them like a hawk as the were crisp after only a couple of minutes or so.
Thanks for all your support