BBC "6.5" Special

I would like to obtain copy of a 1957 "6.5" Special BBC TV show, #4. Does anyone have a copy? I had no luck searching youtube etc.
Our Dolphin Jazz Band was filmed in the St Clements Caves for this show. The subject was "Jazz In The Caves" I still have the script. We are not referred to as "The Dolphin Jazz Band" during the broadcast (we had not yet joined the Union..... Ha Ha!) We were referred to as the Hastings band.
All six band members appeared at the studio and Jo Douglas interviewed our 17 year old trumpet player - Peter Treger, after the film was shown. American blues guitarist Big Bill Broonzy was on the same bill, also Tommy Steel, Vipers Skiffle group, Freddy Mills and other notables.

I wonder if anyone out there has a copy of the 1957 episode 1.4?

Sincerely,
Brian Towers,
trombonist & manager, Dolphin Jazz band at time of the show.
I can be reached at [email protected]