Here's what I said on my blog about them and they are wax based -
Derwent Signature was an expensive range specially designed by Derwent to be highly lightfast. The finest pigments were selected and Signature was the result.
Then Derwent stopped making them. Maybe the high cost? Maybe they didnít have a market for very lightfast pencils? I donít know, but I have heard in some quarters that they werenít as good as they were meant to be. Yes, highly lightfast but there were problems with the casing, the livery, the binding method. You can still get them on eBay and they are still expensive but I like them. They are very creamy, with a dense colour laydown and a nice range of blues and green.