When paying for the meal, I noticed a Belgian guy trying to pay for his £22.50-odd lunch-for-two using his Visa card, which was flatly refused by the manageress.
On enquiry, it seems that the card processing agent for the Botanical Gardens, HSBC, has told the management that it will absolve the restaurant and shop from fraud problems in all Chip & PIN transactions, but not with Chip & Signature. Even for non-UK cards.
The nett result is that the Gardens are now refusing to take all non-PIN cards - full stop, even if the card owner has opted for the card due a disability (i.e. partial sightedness).
Clearly HSBC is driving the Botanical Gardens into this impossible situation, but I do feel the management of the Gardens are partially to blame for the mess.
And that's before you start blaming the plonkers at APACS...