FW451, possibly m.s.no. 7465 and ex 43-8608.
Air-Britain "RAF Aircraft FA100 to FZ999": FW451 Baltimore FW451 13 Sqdn., and Mediterranean Allied Coastal Air Forces Communications Flight. Struck off charge 14.3.46.
No.13 Squadron operated the Marin Baltimore Mk.V from January to October 1944. Converted to Baltimore in Eqypt, flown on operations in Italy from April 1, 1944.
Bases listed during this period: Biferno March 1944, Regina May 2, Tarquinia June 22, Cecina July 18, Perugia Oct 16, 1944. (“Squadrons of the Royal Air Force”, Jim Halley)
MACAF Communications Flight locations reported as 13.7.44 Pomigliano; 26.5.45 Marcianese and disbanded into the Mediterranean & Middle East Communications Flight 1.6.45. (“RAF Flying Training and Support Units since 1912”,Ray Sturtivant)
I could not find any reference to any squadron codes No.13 Squadron might have used on it's Baltimores in Italy.
No.13 Squadron's Record of Events for the relevant months can be viewed and downloaded (no charge if you sign up) from The National Archives. If FW451 was used operationally by the squadron it should be listed along with the individual code letter worn.
To me the single code letter suggest the photograph was taken whilst the aircraft was attached to a communications unit.
Tony Broadhurst