Selborne, we always ask our steward if its OK to leave our hand luggage in the cabin while we go to breakfast and have never been refused, we find it far less hassle than carting hand luggage and a wheelchair.
We try to get back to the cabin before 8:00 but even if we are a bit later there is never any fuss from our steward, in fact we rarely see them, although the bedding and towels have often been removed.
We then do exactly what you did today and head straight for the gangway, and never have a problem getting straight off, and in fact it's often very quiet even though it should be well into the disembarcation procedure.
In comparison we were given an 8:30 disembarvation time on our Princess cruise, but they were running well ahead of schedule and were well past our Yellow 2 luggage time by that time, and we were running a bit late. As a result most of the Yellow luggage had gone when we got to the luggage hall and ours was very easy to identify.
That is maybe something P&O could consider changing, instead of having the luggage in deck order.