01/22/2003. Remarks by Chris Pinn: "Prior to the outbreak of WW II the RAF was very interested in the PBY (later common known as Catalina). A civil variant designated 28-5 (NX21732) was sold to the RAF. Serialed P9630 and marked N P9630, it was ferried from San Diego to the Marine Aircraft Experimental Establishment at Felixstowe (Suffolk, England) in July 1939 for evaluation. The RAF was impressed! Depending on the source, the aircraft either crashed or burned out at its moorings after an air attack.
This was the first transatlantic delivery of a military aircraft in WW II. It's my
assumption that the 'N' was an attempt to make it look like a civil aircraft at a
time when the US was not in the war."