Challenge TV is having one more final try at getting TVS Catchphrase. This does mean someone will have to look out the archive/paperwork/ ex employers IF some progress is actually made. Hold your horse its a very long way away yet.
The main reason why DW episodes are still turning up is because there were sent around the world. The is a chance somewhere in the ITV archive some copies could be held since like crossroads etc things were moved around. of ITV would have to look out for stuff, while cleaning out the archives.
The point about "Brian Henson" for him to be puzzled is puzzling, since there have not released a proper UK series dics, unless the trouble has been really lazy DVD companies like HIT and who ever it is now.
HIT did ask Hensons archive about this and look high and low, and never got a proper answers, hence the reason why HIT never released a full DVD set.
I have to ask Anathema, what is the plan, once you have found all the episodes? Will copies be sent to the BFI? To Henson? will you continue to look for better copies of certain episodes?