Hello John and Pilot DAR,
Very many thanks your prompt replies. John: Thank you for pointing out that the date of the crash was 26.4.1940 -the pale blue and very faint carbon copy of the crash investigator's report at the National Archives was either 26 or 28! He makes no mention of a T3+?? operational code marking (which had been painted over by the Norwegians when they 'nicked' it) but did mention a build date of 8.9.1939. I suppose the T3+?? must have come from the other sources you have mentioned.
The aircraft was from the German ship Admiral Hipper just prior to it being rammed by HMS Glowworm whose skipper received a posthumous VC. Due to bad weather and/or the sea battle the Arado was unable to return and landed in a Norwegian fjord short of fuel where it was commandeered.
Thanks to both of you for your help - I will be making further enquiries.
Peter