Considering British FreeSat channel CBS Action, is also a sponsor, and will presumably be filming links, to go before their endless reruns of TOS-R and TNG - you would expect this to be a more than halfway decent event. Or else they wouldn't exactly have anything to put on camera, apart from a sea of disgruntled faces... in ill-fitting costumes, naturally.
The current CBS con ad trailer shown before TNG is nothing more than a few very close up shots, many of them in semi darkness because Shamasters seem not to like having lights, of Brent Spiner and Chase Masterson, and a short interview with Gates McFadden at Klepto. No event attendees were filmed in any detail.
I've no idea what's led CBS to think any more than a few hundred people will be interested in this, especially with the ticket prices and Shamasters bad reputation amongst UK Trek fans and other organisers. It's all really strange. It will do CBS more damage if they film this event and it's two thirds empty.