I think softly softly's find is a better fit. Leslie Pope Sedgwick was commissioned into the East Surrey Regt in Sept 1915 and by the time of his marriage in August 1916 he is identified as being in the Royal Flying Corps. Tom Bowling Sedgwick, on the other hand, wasn't commissioned until 1918, so he couldn't have been in Abeele in 1916 as Lt.
In case Lesley Pope Sedgwick is also the wrong man, there is a 2Lt Leo Murray Sedgwick with the Canadian Army who appears to have been attached to the RFC, although this information is based solely on a note on Leslie Pope Sedgwick's RAF record card correcting an incorrect entry.