Petlas seem to very difficult to get hold off, when I bought mine I bought the tyre importers last remaining stock.
They don't look to bad hadn't seen those before if only I had the pennies I'd buy five.
Tracgrips wern't the only tyre fitted to the Ferret but it depends on where the Ferret was operated.
These look like the continental type of tyre that Chris has on his
http://www.ferret-fv701.co.uk/inservice/badgergrp11.jpg
These seem to be a sand type of tyre
http://www.ferret-fv701.co.uk/mnuls/08bb65smllr.JPG
If you're only doing low milage Tracgrips are o.k. but you still can't past the fact that most if not all Tracgrip tyre stocks r 20 plus years old.