Sorry I didn't reply sooner I've been away.
Just found this link
http://www.paragonmartialarts.co.uk/acatalog/Footwear.html
These appear to be the same as mine but have a velcro closer, perhaps thats a new thing... mine have a metal hook and eye closer at the back.
Sealskins a waterproof socks using a porelle waterproof breathable membrane, they are quite stretchy. For wearing inside tabi you will probably need to get a size larger than you would normaly. Put the socks on with space left at the toe section then push the sock between your toes, adjust the sock and put your foot in the boot. It can be quite tricky to get it comfortable if you're not used to wearing them like this.
I would also recomend wearing a pair of army wool puttees (spel?) over the top of the Tabi (Polar proof these) for extra protection and weather proofing.
Then go get stealthy in the woods