You keep talking about a gap that doesn't exist while not acknowledging one (below) that does. Strange!!!
European traders are closing out their positions for their trading days. London/Frankfurt close both reflect the European session close - it's more just a matter of what any trader is used to. I just hung around too many oil traders biased by London session opens/closes in a prior life. There can be profit taking tendencies heading into London close (approaching 11:30ET, with 2-week exceptions for UK Summer Time differences). London/European session ES volumes trade notably more contracts than Asian session, so individually it's been more useful to me.