Thanks to our anonymous Trekkie Friend who spotted this. Showmasters who run the Collectormania events might be involved. 
This post was seen on their forum today, posted shortly after Star Trek London’s announcement:
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Hi everyone, 

Showmasters are always willing to help friends who have exciting projects and this is no exception; this is going to be big and we’re guessing most of the Showmasters team will be there – so make sure you sign up to get to know the full details first. 

We already know what’s going on, yeah, we’re really good friends, and can’t recommend enough that you get signed up – Is London Ready?

Join Starfleet now!

see for yourself on Showmasters Forum.

That said, they don’t say they are partners or directly involved. Just that they are ‘friends and know what is going on’.
Whilst it says most of the Showmasters team will be there, it doesn’t specify in what capacity.

This evidence adds weight to the hypothesis that this is a convention but it is not conclusive.

Lets look for more clues….