Supermarine Southampton II

I’m trying to establish a chronology for the early days of metal construction at Supermarine and have a couple of questions. Does anyone know the registration date or first flight day for the prototype Southampton II, N218? Also this aircraft is said to have been part of the Scandinavian capitals tour in Aug/Sept 1927 along with the Iris II, Singapore and Valkyrie but to have had a wooden hull. Was this N218 or another Southampton?

Thanks