Hi Kev,
I’m no expert on Luftwaffe night bombing strategy, but I would discount the Ju88C’s of NJG2 as being responsible for dropping bombs. The Ju88C was a Zerstorer/Nightfighter model, rather than a bomber, and NJG2 were probably carrying out night intruder sorties against allied aircraft. If your information is correct, then it was most likely a He111 responsible for the Walsall bombing.