The GW programme is pretty hopeless about providing info to the GW website which is, in fact, run by the magazine which has Monty Don as a regular contributor but not an editor. Beechgrove, produced independently in Scotland, has a very good factsheet for each programme and with back issues available.
The Gardeners' World show began 21 years ago as a spin off from the TV programme and was run by the BBC Haymarket Publications dept. For many years now it has been run in partnership with the RHS which organises its floral and plant content and has, for the last few years, been combined with BBC Good Food and Countryfile shows.
If you want to know more about the GW show, you need to go to the RHS website.