Been in london only twice in my life, but i know this buiding.
The Hall of "free" thinkers, but you have to admit adeclaration of belief in any deity. (not so free)
Pagan is not one of them
Freemason lodges in France also accepts atheists/pagan's .
I looked it up, since it was told to me in the Netherlands after been there (about 18 years back)i found the next text (but then there is no international umbrella structure as far as i know)
The most commonly shared rules for Recognition (based on Regularity) are those given by the United Grand Lodge of England in 1929:
The Grand Lodge should be established by an existing regular Grand Lodge, or by at least three regular lodges.
A belief in a supreme being and scripture is a condition of membership.
Initiates should take their vows on that scripture.
Only men can be admitted, and no relationship exists with mixed lodges.
The Grand Lodge has complete control over the first three degrees, and is not subject to another body.
All lodges shall display a volume of scripture with the square and compasses while in session.
There is no discussion of politics or religion.
"Ancient landmarks, customs and usages" observed.
perhaps this are outdated "rules"
I don't know in real life today if they still adhere too the 1929 rules, i do know that grand lodges of other country's, not don't necessarily recognize other grand lodges of countries for what they are, if there are connections they talk about "amity" with the other if it is mutual.