Anecdotally, I once found myself IN this pet shop. It was in the Caledonian Road, North London. I wandered in - I was passing and needed something or other - and realised it looked familiar. Then I saw the signed picture behind the counter. It was a still of John and Michael in that "very boutique".
The shop-owner explained that when they'd done the bit on TV, they'd HAD to do it in the studio - for the audience reaction. But since this was for the FILM ("And Now For Something Completely Different") there would be no live audience. And with the superior definition of a film, a set just wouldn't MAKE it. Real pet shops have CLUTTER. And so they'd gone and found one - HIS.
I don't know if the shop is still there - if it is, the guy has probably made more money letting people be photographed there (like on the crossing outside the Abbey Road studios) than he has selling Norwegian Blue parrots!