My goodness! A Guinness advert emphasising its Englishness?

Can it be true? An essential English ingredient at the heart of every Guinness? In fact the Guinness Hop Farms in Bodiam East Sussex were sold off just a couple of years after this advert was made, after 100 years of service. Guinness has a long history of peculiar adverts, but the foregrounding of rural England somehow makes this one of the most unusual. Records suggest the ad was co-directed by Nicholas Roeg, in between features Don't Look Now (1973) and The Man Who Fell to Earth (1976).

Advertisement for bottled Guinness. Hop harvest at Bodiam Farm in Sussex.
Voiceover: `...So, if anyone ever asks you how Guinness is made, you'll know
what to tell them!' A woman is with her friend at a pub drinking Guinness.
The friend tells her `You'll never guess how it's made...` and she says `Don't
tell me, it grows on trees!'