Rex, I think you'll find that P&O stands for Peninsular and Oriental (Steam Navigation Company, to give it its full title), not Pacific and Orient. P&O is now part of the Carnival Corporation, who also own Cunard and many others.
You're quite right about the funnel colours, I well remember the big white or buff hulled ships with buff funnels coming into Sydney harbour, ships such as Orcades, Orsova and the old Oriana. The three mentioned were owned by the Orient Line and transferred to P&O when the Orient Line was acquired by P&O.
Peter.