I’m indebted to George Simmers’s blog for the information that the extended interviews are available online here. Very well worth watching, I promise. When I watched the programme, I didn’t realise that one interviewee was the same Charles Carrington who wrote A Subaltern’s War, one of the best war memoirs I’ve read.
Edit: I've just found out that many (all, even?) episodes of the 1964 series are available on YouTube. Episode one here. The accents don’t sound so very different from wartime ones.