I found a bit about this on a flight sim creation.

Can't vouch for its accuracy but you know what the sim types are like. It suggests that this is a trim for when flaps are deployed and alter the pitch of the aircract, the "elevators" are automatically deployed to compensate for the attitude of the aircraft. Hey hey clearly "Bad attitude"

It makes sense, but I cant vouch for its accuracy, so would be worth finding out incase the elevators are not powerful enough Ronnie. I notice there are a lot of other bits on the tail section......

Gazzer