> They were in no way pirated, they were recorded under the UK's copyright exemption for this purpose.

That's a bit of a grey area as IIRC videotaping TV was allowed for "time-shifting", but not for keeping long term. Whether that counts as pirating is debatable.

> Also that is a vanishingly small amount of content

Yes, that was one instance that I was recalling, but I think there's been other examples of missing episodes such as Hancock's Half Hour. I just think it's a shame that productions of historical value are lost due to the legality of personal copying although that's more relevant to shows from the 80s/90s/2000s when copying technology was widely available.