Thank you to everyone who commented to offer support and/or advice after the Wetherspoon's incident.
I wrote a letter of formal complaint and following Jim's advice I sent a copy to the local licensing authority. I received prompt responses to both letters, the licensing authority telling me that my
"complaint is currently being investigated and [they] will write to you again with the outcome"
They also gave a (direct line) phone number and suggested if I have any queries I should contact them
Wetherspoons however simply said
"Thank you for your letter we received yesterday and for taking the time to write to us.
We are currently investigating the issues you raised and will be in touch in due course"
I'm very touched and grateful for the support that other bloggers have shown over this issue, Jackart posted on the subject, and Stonehead has not only posted on the subject but emailed Wetherspoons himself to let them know what he thinks. Gowen and Humaniform (who is I think Matt Wardman) have also posted on the subject.
I'll keep you all posted as and when I hear anything.