Dunno. A few seconds googling yields the closest heraldic
device match for the bird with the 133 "eagle" sqn badge, but
133 sqn never flew Battles, according to wikipedia. Other
birds include 2, 20, 37, 56, 63, 71, 151, 201, 420 sqns,
but none of them in the style shown, and of them only
63 flew Battles, and their bird is a phoenix in flames.
Of course this quick search didn't come up with anywhere
near all the insignia for all the possible sqns.
Beyond that I can only observe that birds spreadeagled
like that I've mostly seen on eastern european heraldry.
...OK, dug a bit further, the only candidate which suggests
itself is 103sqn, which has a black swan insignia, which is
relatively close to the overall appearance of the pennant bird,
though I suspect the latter is supposed to be a black hawk
of some sort, and as with most of the bird insignia, the black
swan is shown in semi-profile and lifelike, rather than the
medieval stylized spreadeagle of the pennant.