I have an early Bonney tappet wrench, it only has the Chrome-Vanadium and CV-Circle markings. It has a part number of AT8053 and is 3/8 W by 7/16 W in size. The date code on the rear is C.T and if my math is correct this puts this at March 1942? So what I'm hoping is I have a British Military wrench since the sizes are in Whitworth. Ok teachers, grade my homework assignment, how bad did I do? 

Hello, moparthug . Whitworth wrenches were bolt sizes , not sizes across the flats , as far as I know. I don't think Whitworth sizing  had any connection to British Military .

Made during the war, but probably not military usage.  All military items in Great Britain were marked with the Broad Arrow and usually dated.

It is part of the toolset in the picture.
-Don

So, now you've got a start on your very own Spitfire, Hurricane, Lancaster...all you need is the other tools, a Merlin engine, an airplane of the right type, a dose of insanity...

My mistake American made tools wouldn't have the broad arrow.

A while back I purchased a rather large cloth bag full of Whitworth wrenches, over 45 wrenches, many of which had British military marking.  The marks were the Broad Arrow, the A.M. Crown (Air Ministry?), and several wrenches hand engraved with RCAF (Royal Canadian Air Force).  Some of the wrenches had forged dates ike 1941 and 1944.
Broad Arrow was forged or stamped.
A.M. Crown stamped.
TW wrench with 1941 date (T Williams)

Al

You see, THIS is why I always bring my tool questions here! I would have never guessed this wrench was part of a set of tools for a Packard (USA) built Rolls-Royce Merlin engine for a P-51 Mustang in 1942-1943. Thanks Don for the info and pic. The collective knowledge on this site is staggering, you guys are awesome.