1972 and 1974 + movie are out on DVD already but I just heard that a possible DVD release is due in 2015 source: Network's Facebook page

Really hope this is true.

A very exciting prospect. Fingers crossed they can indeed seal a deal.

Wow!. That would be marvellous if they could pull it off. I have been waiting for more episodes to be released for years. Network say they never usually comment on future releases in case it causes the release not to happen. I won't believe it's true until it appears on their website.