In terms of a new B&M coaster, I'm not sure what possibilities we have left, in regards of a new coaster at Thorpe.
We've already got the inverter and wing rider.
A hyper coaster (but on a smaller scale) could work
A dive coaster may be a bit too similar to Saw, so it would need to have a more impressive layout and theming (plus they can't go underground at Thorpe)
Flying coaster may be regarded to similar to Swarm, unless it has a completely unique and different layout
Sit down and floor less are too similar to Colossus, even if they had different layouts
Think that's about it.
I would certainly love to see a woodie as the next big coaster as the new ones made by the likes of GCI, GG and the like in parks in the world look fantastic and having ridden Megafobia which is a fantastic coaster I can say it would suit the ride line up perfectly.
If Merlin are still uncertain on the woodie idea, they need to see how popular and well acclaimed these new rides are, plus their own one in Heide,and if they're still not confident (dare I say it), just theme it around something like the Hunger Games as that would surely give them more faith.
As for Derron Brown-the ride, I can't see this working, especially one a wooden coaster. Having watched one of his performances and the way it was executed and performed, I can say a Derron brown theme would work much better in a dark ride setting, something like an interactive scenic ride or the likes.