Please see below a chart of the cabins and grades of the wheelchair accessible cabins on the P&O ships, I hope this help people out.
Iona, inside accessible cabins have been reclassified as PARTIALLY ACCESSIBLE. This is due to the turning circle not being big enough for certain mobility aids, such as scooters, basically they are standard cabins with accessible elements- contact P&O before booking.
Arvia, PARTIALLY ACCESSIBLE CABINS are grades, PB, PC, PD, PE, PF. This is due to the turning circle not being big enough for certain mobility aids, such as scooters, these are suitable for guests bringing non motorised up right assistive mobility devices and who do not require the use of a wheelchair, scooter or other similar assistive devices. These are standard cabins that have accessible elements, these cabins are all shower only.