It's from 1973. Was the final broadcast master on film, or U-Matic / Type C tape or similar? If it was tape, no one has a machine that can play U-Matic or Type C tapes anymore. Well, the BBC Archives probably do. But let's hope the archives had the money to transfer it to something in the 80s or 90s, back when the tape was hopefully still in good shape. (Edit: Type C was introduced in 1976! It would have had to have been quadruplex tape, if it was tape. There are only a handful of working quad players in the world.)
And video tape, well, it was very expensive. And you could reuse it. Most video tape from the 70s got the same treatment parchment did in medieval times. Sometimes erased and reused for scrap paper, even if it had originally been a work by Aristotle.
Generally material was done on film at that time. 1000 ft of 16 mm film -- enough for 1 half-hour episode -- cost about $500. Keep an archival copy of everything broadcast at the time, would literally have cost many millions of pounds a year just to make a copy of the film stock. And they would need to do that, as you can't really rely on standard film stock to be archiveable. It needs to be good stuff. A lot of film that is 50 years old today is now literally falling apart. So the archival department would have needed to be be constantly moving old, fragile film material to current media, just as with video tape. That is labour intensive, and accordingly expensive.
Meanwhile, in private life, I am considering how to transfer some rare materials from laserdisc ... later, perhaps, but also unpopular.
But overall, I can forgive some of the older material but even the newer business just seems to vanish!
It's not that easy; you can't just put a hard drive or SSD in a safe and expect it will work after 20 or 50 years. If anything it's harder and more expensive today, because you can do that with a reel of tape (it does degrade, but much slower).
The main thing that's changed it that people realized there things are actually useful to keep around. Much of the stuff that was erased or thrown out was done just because people didn't think anyone would care.
> Long-standing agreements with UK talent and musicians unions made it difficult too. Most UK television programmes were only ever contracted for one domestic repeat broadcast and so once a programme had been repeated once, there was often considered to be no point in further retaining the transmission master. It’s purpose had been served.
From: https://www.bbc.co.uk/rd/blog/2017-12-morecambe-wise-video-f...