However, I have just come across something called Cookamesh, which seems very similar.
It is a flexible and reusable PTFE mesh sheet, good for up to 500 degrees F.
It is available in some Lakeland branches and assorted other online cookshops. I have also found it on eBay, and there is also an Amazon.co.uk seller selling them.
They come in 3 sizes - 330mm x 400mm, 240mm x 370mmm and a 320mm circle. I picked up one off eBay for just a couple of quid (except the seller sent me the wrong one - circular, rather than rectangular).
I've never handled a frogmat, but these look exactly like what I have seen pictures of.
