A good reason why it wouldn't be an Arado 234 is that the Ar 234 B-2, used for reconnaissance over the North Sea and UK east coast in March, was a single-seater. 1.(F)/123 was the unit doing the UK reconnaissance at that point and its aircraft strength
increased by one between 2 and 9 March while its pilot strength remained unchanged.
I think that far from wanting to cover it up the RAF would have been delighted to have another example of the Ar 234, just over a week after acquiring their first one in Western Germany. There is ample documentation of that find and of the Ar 234 wreck found in Northern Italy in April 1945.
You might find
this book helpful (and it's cheap): "Air Raid!: The Enemy Air Offensive over East Anglia 1939-45" by Michael J.F. Bowyer.
I no longer have my copy, so I can't check it for you.