Last time they sent me to the JetBlue area for security (I think that is the Margaritaville one you are referring to msm2000uk, directly in front of the escalators to the E-gate transport?) as there is a separate TSA Pre line there but it was huge and didn't seem to be moving, so I went back to the security to the left of the BA desk and they put a TSA Pre marker in with my luggage going through the scanner so I didn't need to take anything out.

It would be nice if they would start doing what the AA Flagship check-in do for F pax in terms of security, mildly embarrassing as it might be (I'll admit to not caring about that in the slightest...).