Given that the trays on the new "enhanced" security screening lines at T5 are designed to take a 56cm case exactly, I wouldn't hold your breath.

Incidentally, my experience at GLA suggest that these new "improved" baggage screening lines are actually slower than the old ones they replace.

Domestic security at GLA has two lines, one of each type and I've been tracking passneger flows whilst waiting in the queues and the old style line is inevitably faster than the new T5 style one.