Thanks Alex
Yes PDU is a well known abbreviation.
Thanks also for the added info regarding what EA stands for. I suspected it could be something added to Vickers Armstrong, but had nothing to show for my thoughts...
Well, since I don't believe Jim Halley took 610 Sq out of a Top Hat I am still rather convinced 610 Sq used the aircraft. Perhaps it was so new and lost almost immediately after delivery, that the ORB never recorded it?
Cheers
Stig