Bas,
The a/c on May 14 of 1.(F)/121 was not a He111, but a Ju88A-1. Other than that location, time and crew are correct as mentioned.
In general the two claims of He111's of Stab./KG54 by Brongers and all others who copy his list are based on the well-known files of the late Mr Weiss. Interestingly, though, is that the time is mentioned as 14.30 pm, which was almost exactly the timing of the Rotterdam bomb raid by the entire KG54.
As far as I know no losses were reported on this raid (Dutch AA fire was effectively absent at that time), so that leaves two obvious options.
- The claims are simply false/confused/mistakes and probably impossible to trace back where this mistake was made.
- If they are true it would imply that the Stab Staffel (some 4-6 aircraft at most) of KG54 did not participate in the bombing of Rotterdam, apparently flew on to Zeeland, attacked shipping there and then two got shot down without leaving a trace.
Since I find the second scenario more unlikely than the first, I tend to believe the first one until more hard proofs of the other come available. In the meantime I still believe the confusion is with the two Heinkels of Stab./KG4 which are listed under May 17. See both Brongers and Peter Cornwell. also Wim de Meester has aarently done a lot of investigation into these losses, see
http://www.wingstovictory.nl/database/database.php. Also there you'll find that the May 15 crashes are only based on reports from French naval forces, but are not confirmed by any real evidence of a crash.
Regards, Pieter