Thank you, Kempie.
Odd, I had a premonition that it would be you that
could provide an answer.
Another query arises from the Wikipedia reference:
are the badges of rank for Commissioner and
Deputy Commissioner exactly as represented, or
have they been transposed - the DC appears to have
an extra 'pip' ?
Although it goes against perceived logic the rank epaulettes have not been transposed.
It appears that placing two pips side-by-side (instead of the more usual one-over-another) is meant to signify a subordinate role.
Compare these two pictures of Sir Ian Blair... both are used for articles in which he is named as the Met. Commissioner but in the first he appears younger and with fewer medal ribbons which I would take as proof of him holding the lower rank at that time.
It's exactly as you say, Kempie, though as you point
out, the logic is a tad illogical.
With army insignia to act as templates, it makes one
wonder by what mental sleight-of-hand this particular
configuration was devised.
Psychologically, the double pip has a better gestalt
than the more-senior single pip, but then, 'ours not
to reason why' as Tennyson might have observed.
Thanks again, Kempie, for 'doing the honours'. I am
obliged. Stay around, eh ?