I think that's the 24v electrical connection we're seeing there. The little power supply cart is not one I'm familiar with though.The oxygen filler would have been higher up and slightly further back, roughly in line with the centre of the panel visible behind and below the electrical connection. To reach the input for the oxygen system a little hatch needed to be opened, and I don't see that.The flip cover for the 24v supply was much smaller.
I can't see the oxygen filler hatch in the image and can't remember off the top of my head if it was moved on some later variants (I don't think so, it's there on the G at Hendon).
Cheers
Steve
You're quite right Steve.
The 'power cart' is a different design to what I'd expect to see, which made me think it was an oxygen cart. But then, there aren't any oxy bottles on show, and the 'hose' is a bit 'thin' too !
I've come across some examples where the "splinter" pattern had soft curves instead of the sharp angular pattern...it may have been a hasty job in the field in preparation for an operation or who knows, really.