Hi all,
I am trying to understand (and properly translate) a caption of a RAF Spitifre fighter lying on the ground upside down with a caption:

"And there I was on my back with nothing on the clock a hanging on my straps."

I have asked Mr. Google for help with epxression "nothing on the clock" and I got following answer at https://en.wikipedia.org/wiki/RAF_slang:
"Nothing on the clock but Smiths - Fuel and other such dials down to zero leaving only the instrument makers name."

So is my understandiong of the caption correct?

The pilto was hanging in his harness upside down with all instruments showing zero in an aircrfat lying upside down on the ground.
(This fully corresponds with the photo).