They're not extinct. I have one at my feet! :D (Snoring)
As previously said there is a working clumber spaniel society:
http://www.workingclumber.co.uk/They are slow methodical workers, great game finders with fantastic noses. TH has a very soft mouth. But beware, they are fiends to train. Plus they have lots of "personality" around the home.
Debbie Zurick, Secretary of the WCSS, is doing a great job raising their profile. They are not popular and don't do well at field trials as their style is so radically different from the other spaniels. They do very well at the minor spaniel trials though.
Ones with working breeding are difficult to find and puppies now start in excess of £600.