Ross, I was all set to chase the AP when Air Ministry rather timely , swooped in with its contents. Thank you both.
Back to the problem…
Air Ministry observes that the cockpit photo shows the clock as flush fitting, with red time of flight hands, no sweep second hand and no obvious winder, ie hidden behind the panel.
That description matches just about perfectly clocks 6A/1104 Luminous or 6A/1105 Non Luminous, these clocks are often shown in pre war drawings or photos of instrument panels
to be flush fitting, possibly using either the C type clamp or spacers. Picture 1 shows 1104/1105 and the same movement with an extension winder fitted , ie to reach up and under.
So it would appear that 6a/1104,6A/1105 are the clocks in question in that particular publication.
I have re checked AP 1275 1930 and AP 1275A 1938 and 6A/944 is not listed or mentioned as superseded .
This makes me speculate that it was a wartime stop gap measure using available clock movements…up market ones going by the specs!!
Photo 2 Shows The M1, 6A/ 1105 and 6A/581 a MkIII with Chronograph movement, to help understand the scale of the various contenders.
I have not seen a smaller chronograph movement in any other Air Ministry clocks…..yet.

Thanks to all for the help
Regards Mike