Well done ,
@T4tomo , that's the spot.
I first cycled this way on my very first Friday night ride to the coast, 20th MAy 2016, which means I posted the photo pretty much 7 years later on the nose.
We went past this soon after the halfway stop, hence "over halfway there".
@Dogtrousers - it was 5.40 in the morning we went past, so it should have been light enough to notice. I think we had a chat about pronunciation of the placename "Slaugham" a few minutes later; not that I can put a face to your name, but the discussion did continue on the forum afterwards; you also posted a GPX of the route!
As it's a not a natural lake, a search of cyclechat for my mentions of the words "pond" would have identified the location immediately!
The other clues:
Flying was both a clue to the destination (Shoreham airfield) and with extinct birds a reference to ride leader "Flying Dodo".
Over to you T4tomo