Deplaning should take place from the front to the back. Remember, the cost of the ticket or your frequent flyer status generally dictates if you sit at the front (premium/elite) or the back (cheap seats).

Front should have highest priority.

On the other hand, boarding should also be from front to back using the same logic as above. If you pay premium price you should get the overhead space - not the cheap seat artists who carry on 5 bags and conveniently leave them in the overhead bins for the premium seats. The few seconds extra while boarding will balance off the time it takes to find storage for the last passengers at the front of the plane who find there is no bin space left.

BA - why do you always board World Traveler PLUS passengers LAST? Premium seats - last to board - generally no bin space.

Azamaraal