Rescued nozzle this morning. I did disconnect the filler tube at the base
of the neck from the tank in case it was resting in that horizontal part
and to prevent me pushing it into the tank if it wasn't.

The Netto £4.99 floor matts made lying on the wet concrete drive in light
rain a much more pleasant experience from not getting really wet or cold
but also rather softer than concrete. I think I might get some more.

It was lodged in the bend at the base the filler neck, a long flexable
grabber caught it on the second attempt.

http://www.choiceful.com/choiceful-id-75494-Draper-Fully-Flexible-Claw-Pic
kup-Tool.html

Damn useful tool that and the mirror on a stick for looking down the ends
of the disconnected filler pipe.

As to an anti-syphon grid, once I'd got the nozzle out I couldn't get the
grabber to go any further down no matter how I twisted on waggled it so
there may well be a grid or lip designed to stop tubes penetrating to the
tank.