Seek and you will find :)
Found a couple more items from APO 3. these show clearly the Red Cachet
BRITISH RED CROSS & ORDER OF St JOHN * BASE P.O. * Date as postmarks 24 AVR & 7 AOUT ---- French ?
Interesting First censored 4 / 2986 and the later cover 5 / 2386
Enjoy
Chris
One for Alan and his records
Have found a second Red X cover with APO 3 Cancel and censor 5/ 2386 Dated 13 October 1917. I think we can confirm this replaced the earlier Type 4 / 2986
Chris