I did a little research a couple of years ago which corresponds with Marks number of 28 surviving episodes of "Out of Town". They were available on nine DVDs, 3 or 4 episodes on each DVD, published by Contender Entertainment Group (2004), now Entertainment One Ltd (who no longer list the episodes).
Paul Peacocks "Jack Hargreaves - A Portrait" was published in 2006 by Farming Books and Videos Ltd (no longer in existence) and contains a full listing of Out of Town broadcasts from the first in July 1960 to the last in 1982, over 1,000 editions, the huge majority of which were never retained by Southern Television.
"Old Country" was broadcast from 1983 to October 1985. It's unclear how many episodes were retained but some of the youtube clips listed as Out of Town are definately not!
"Gone Fishing" was first broadcast in 1959 again by Southern Television. Just 28 episodes, none of which were archived.
I had the distinct pleasure of meeting and talking with Jack Hargreaves on two occassions on the Stour. So many years later, I still vividly recall those meetings, brilliant!
"Cheerio"