Non priority-security is open during the rush-hours. It is easy to check looking at the monitors visible even downstairs. Annoyingly, the priority security is closed during the late evenings even though the queues are not long at that time. Any priority lane accepts any FF card allowing the use of it (eg Star Gold members are allowed to use T2 and OWEs are allowed to use T1 priority security).

The only trick is BA. Only OWEs (including BA Gold) using BA CE are allowed (this is not written anywhere) . BA CE passengers without OWE are not allowed. BA golds flying AY (and other OW?)are always accepted.