I thought it was only the UK that thought registering a classic bike might be terrorist activity! In the UK they make a meal out of re registering classic bikes, when I was sixteen I got a moped with only a number plate and no documents. I hand wrote a letter to the Dvla and two weeks later the sent me a registration document, that’s how easy it used to be😀!
Why they assume people who just want to ride old bikes are avoiding vat and tax is beyond me!
good luck getting it sorted out