Rickman-Commando

maybe contact DVLA and see if they can agree to change to Rickman. This is often done for other Rickman frames.

Was it built by Rickman or was it a kit? … There could be a number of reasons why the maker is shown as Norton - eg who ever registered it may have put Norton in the makers box on the V55/5, or they used the commando registration number to register it (it was easier to do this a few years ago) care needs to be taken that it doesn’t open a can of worms - the last thing you’ll want is a Q if it turns out its bearing the original commando registration details.

( I used to work in a VRO)

Dan 

Dan is almost certainly correct here. The UK had no "Type Approval" in the 1970s so replacing a frame with another type did not invalidate a registration if the same number was used.

Have you checked to see if your frame has a Norton Commando series frame number, or does it have a Rickman-applied number ? Which of these options (if either ! ) is shown on the UK V5 registration document ?

Discretion is often a good idea when referring to licensing matters on the internet.It's best not to post numbers.

The most likely scenario is that the original builder took a donor machine and transferred the numbers over. The German / Continental European (due to pressure from Germany) Type Approval system was completely alien to the historic UK way of working which allowed motorcycle and car "special" builders a great degree of freedom to change components as long as a basic safety test was passed.

https://www.gov.uk/vehicle-registration/q-registration-numbers

Basically it's for vehicles that have been built up from spare parts of indeterminate origin (or the builder couldn't be bothered to provide DVLA with the information). For example, a race bike that was never used on the road and doesn't conform to any known production machine. Q-plates are quite unpopular and, if you can show with period photographs etc., some history of the machine (or one like it) you can apply for an age related registration; something that Triton builders often do. NOC can help in this regard. Age usually goes with frame and/or engine. This is why frames with registration documents (V5) sell for more than a frame alone.

Take a look under the "records" tab on the menu at the top of the page.

With a "Q" plate, it's a puzzle that it was registered as a Norton, but I'm not sure that it could be corrected if the machine is not available for inspection in the UK.

DVLA do accept the Rickman Metisse Historic Register as an authority for "dating" letters 

How does the system work in Germany ? Could you start from the beginning ?

There are certainly Rickmans registered as such in the UK.

The good news is that as a Q plate, as said by others this Number is for kit built type vehicles, so it is likely that it has been correctly registered. My guess is that the person who registered it put Norton as the maker on the V55/5 registration application, or possibly they has Norton on the tank (as my Metisse does) and the vehicle inspector wrote it as that. There was a time when you could phone DVLA (or DVLC as it was then) and speak to a human and ask if it was possible to change the manufactures name, I don’t know if you can do that now (speak to someone that is!). 

My guess is that they would want you to go through the registration process again, which might be a pain depending on what they want in respect of type approval. 

As Richard says maybe the best thing is to try the Rickman Historic register as a starter (they have a facebook page) Kevin Downer is your man and see if anything they can give you will satisfy the Germans?

Out of interest if you don't tell the Germans that is a Rickman frame, how will they know? If the bike match’s the V5 wont that be enough?