Discussion on the Air-Britain forum centres around this photo of DD867 from the IWM:
A clearer side-on image can be found at:

The IWM caption refers to it being a 423 Sqn aircraft, and it does indeed seem to have served with this squadron according to the relevant Air-Britain serials book and the Air-Britain Sunderland history "Ocean Sentinel", which lists its owners as:
10 (RAAF) Sqn
423 Sqn
131 (C) OTU
57 MU - struck from there

The code listed for it with 423 Sqn is 3-G, which as can be seen from the photo is not correct. It wears code 2-G.
The problem is that I am told that the Sunderland units based in Northern Ireland used the following digit codes:
201 Sqn: 1
422 Sqn: 2
423 Sqn: 3

So as DD867 was coded 2-G, it should theoretically be a 422 Sqn aircraft.
Does anyone have access to the original aircraft record card please?