Sad to hear this. I've been watching a lot of his stuff in the last few years. I finally got to see all the episodes of Space 1999, which I missed when it was on the air here, and received a Thunderbirds Six DVD for christmas several years ago. Also watched some other films he worked on.
A real pioneer.
One of the last of the Stargate series episodes (no.200?) had a tribute to his Thunderbirds style marionettes. Unfortunately the SG1 puppet's strings were cut by the stargate wormhole effect.