I had assumed that my photo shows a 223 Sqn Baltimore and the X was a Squadron designation. As you can see one of the examples of the markings below is a 223 Sqn aircraft and the X is also an option.
The decals in this kit provide markings for four examples:
I see. But I have seen a couple of other pictures of Baltomores marked with the "X" while being of different serials but belonged to different squadrons.Anyway the bombers used in the North Africa / the MTO, didn't wear a squadron code letters that consisted of two signs but not of one. If your assuming would be correct , all kites of the 223 Squadron had to wear the same letter at the same time. But there are other images of different Baltimores that were marked with different code letters. For instance the AG724.
Peter, from the Sqn ORB I can confirm this is Baltimore AG714 "X" of 203 Sqn. I've been researching my father's time on the Sqn, albeit brief, as he crashed in AG749 on 15 Oct 1942. He and two others survived but sadly the wireless op died. The aircraft burst into flames on crashing. I can't identify your crew though but in Oct 42 Sqn Ldr Slaughter flew X quite often with his crew of P/O Currie, Sgt Levitt and Sgt Curtis. Somewhere to start hopefully - good luck.