[Neil Jones]

That wasn’t quite the answer I was looking for :-) I was just wondering if tapes actually exist in the archive for long lost shows like Gardening  Time.

I know it wasn't the answer you wanted, but it was the answer I wanted to give.
Being a Central show it probably does exist - I wouldn't subscribe to the "Lost Media Wiki" style of thinking where its claimed to be missing even though it probably actually isn't,.

I've no idea if it's still there, but Prime Video once had a bunch of ancient American comedy/variety shows from the 1950s deep within its offerings. I can't see how many people would've been calling for them to be made available, but I guess Amazon figured it made financial sense to boost their range of content.

they'll have got them cheap I would have thought, as a general rule the older something is, the more obscure it is and if it's in black and white (as per production methods at the time), the cheaper it costs to buy.

Must remember Amazon turns over more in a year than the GDP figure of many small countries - if Amazon was a country it would (it says here) be the 14th richest country in the world. They're not short of a bob or two, so even if the 1950s American content was sold to them at a premium 'cos they could see them coming, they can afford it.