That far right-hand lane is for crew and Club Milione members only. I am a Club Milione member and they check my membership card thoroughly every time I go through. As VCE is my home airport, I would say that 50 minutes is cutting it close. BA does have OLCI for VCE now, so if you have OLCI before and do not have any checked luggage, you can go through the "transfers" area. This is immediately on your left after going down the escalator from the gate area. They will re-screen you and you'll go back up the escalator to the gate right away. This helps you avoid the main security lanes. However, at that time of night, I do not know if it will be open/manned. If it isn't manned, then just go outside the double-doors and right up through main security.