Pre-War should be polished blue finish.
The barrel should match the serial number.
The magazine looks postwar from what little I can see of it.
Pre war mags have 2 cuts about 3/16" apart coming from the back edge of the floor plate forward. They form a spring catch that secures the floor plate to the base.
That one looks solid and is secured by the center button under spring pressure. That is post war style.
(Canadian Inglis war time mags used the center button catch also but had the spring catch on the base in addition. Inglis mags are marked 'JI' on the lower front spine).
Check the barrel cam slot for crack(s). The pre-war style had a round cut cam slot in the barrel lug that was prone to cracking in use.
They changed that to a squared face forward cut in the cam slot very late in the War and continued it post war.
FWIW,,the */E after the nitro proof stamp is the mark of the Proof Controller at the time to pistol was built and final proofed.
That particular mark was assigned to Jamart Auguste who worked at FN from the mid 1920's to 1959/60.
Not that it means anything!
Serial numbers on pre-war HP's are difficult to sort out. FN would serial number a contract to the customers request. Trying to match #'s with yr/production is very difficult. They made them for several different countrys in varying amounts,,,some specially marked,,some not.
A large number of Pre-War HP's with tangent sites were imported into the US by Navy Arms in the late 80's. They came from China,,just before the Broomhandle flood. Condition was about the same as the Brooms. Some nice,,some not so nice.
The Chinese did contract with FN for a large number of pistols in the 1930's. No special markings were put on them by FN. Many have Chinese markings added there. I don't know of any source of the contract ser# range.
Another possibility,,
The 'A' in a box marking on the left rear of the trigger guard could possibly be the Belgian Military marking Pre-War,,but I'm not absolutely sure.
I can't remember if it was diamond shape or a square the A was inside of.
I just ID'd a Colt 1903 a while back with the Belgian Military mark on it so you'd think I could remember..!