Greg,
Burden's SE5a C1098 was marked V as a C Flight aircraft. The illustration in 56 Sqn RFC/RAF - or as the publishers have it RAF/RFC - is correct. Source: Burden's photo of this SE5a which he sent home and annotated around the edge of the photo, with the colours etc. The markings of SE5a in the photo you posted is very inaccurate, even down to the way the sqdn marking has been applied.
