Reg. No. From Motorbike Frame Number?

[steve@cornwall 100]

Hi all Not car related, but vehicular. I have a new project bin the shape of an eighties mt50 2stroke trials moped. Great fun to use no matter how slow . Now the problem is that prior to being left in a hedge, it has been used as a field bike and lost its registration details. It does have a clear frame number and I understand that although dvla are unhelpful, it is possible to trace the reg from the frame number but requires trade access to hpi or similar. Details on the net are sketchy but does anyone have knowledge of the ability to do this? All help appreciated