Hi Bryan
Thanks for your reply
The following things I have found
In a commentary written by a Sunderland pilot who flew Mk III's
during WWII (Mac is his name) he stated that (at least in
the West African Mk III's) that the following applied on Sunderlands he
flew in

1) Mk III's flew with a single VGO (Vickers Gas Operated) MG (.303 cal)
this was in liu of the twin Brownings usually carried, as the Lufwaffe
was not a threat in that area
(this begs the question when did the Mk III carry twin brownings prior to the Mk IIIa)
This is a 490 Sqn Mk III West Africa

(Photo used for illustration only)
2) Mk III's did not carry the upper mid turret
3) Only Sunderlands based in the UK carried the bow mounted x4 Brownings.
Mac's Mk III (DW109/Q) had the MkII ASV equipment (Yagi aerials etc) so was
not a Mk IIIa
Unfortunately the only photo I have of DW109/Q is at a distance, so the
forward turret is not that clear
Pehaps I may have to go with either a Vacform similar to the photo above or Falcon models sells
the set
Thanks for the replies
Regards
Alan