OK a bit more sectariania, it's somewhat of a diversion, but I think it's relevant to the milieu that 'lexit' support comes from, which is a weird convergence of ex-anarchists and Stalinists.
The Commune originated from Red Star
https://en.wikipedia.org/wiki/Red_Star_(UK)
And Red Star itself originated from AWL (and some other places). You can see David Broder writing about leaving the AWL here: https://shirazsocialist.wordpress.com/2008/08/23/the-awl-israel-and-iran...
https://weeklyworker.co.uk/worker/685/david-broder-no-platformed/
This was all around 2007-10:
Then Socialist Fight in 2017 documents Broder's conversion to Stalinism: https://socialistfight.com/2017/10/27/david-broder-the-renegade-from-tro... - that (incredibly long and boring) blog post also mentions tankie Alex Gordon of the RMT.
Novara's take from 53 minutes:
https://youtu.be/ibz5tHy7OpQ