I think I've solved this one.
Today it's Guide Dogs for the Blind, once again same set up as the others, ring of buckets, sound system and the added novelty of stuffed dogs !!
I asked one of them to see the permit which he did show me, having said that I wouldn't know if it was legit or not.
I then rang Guide Dogs for the Blind who said somebody does collect on their behalf with this type of set up and also collects for Help the Heroes.
From the name she gave me I came up with this;
UK Charity Aid About Charity Aid