On 23 Jul, 15:10, David J wrote:

Is this just a jobsworth flaunting his power, or is there a valid law
in operation here?

Yes, the principle that when on private property the owner may make
whatever rules he or she wishes, so long as they are not racist,
sexist etc. Not permitting dogs (which may soil the place or leave
hairs all over it, or intimidate other customers who do not like dogs)
is an entirely reasonable rule, except when it comes to guide dogs
which you tend to find are permitted in such instances.

Not "jobsworth", IOW, but a reasonable condition of entry, just as it
would equally apply to my house that you don't bring your dog in
because I don't want the smell and hairs everywhere.

Neil