How to get a reg number from the frame number.

Hello ,i wonder if anyone out there knows how to go about finding the reg number for a bike with just the frame and/or engine number?
Thank you.

There are companies that will search for vin to registration number. There is one that offers their services on Facebook

£7.50 if they get a result, no charge if they don’t.

Brilliant, thank you, I will give them a go.