Thank you for your reply Erik.
My machine is identical to the one in the link to your galleries. It has the covers for the gears but is missing the mudguards and a few minor pieces.
Unfortunately I was in too much of a hurry to take the bike down yesterday (the wife has a new puppy and had to have the camera) so I was remiss as to taking photos of the machine complete. It is now down to the frame.
For years my father had told me it was a TT model. I think I need to burst his bubble unless you know something I am missing. Also my partner in the project thinks we have a 2 speed and that it is earlier then the 27 I thought it might be. I based my opinion mainly on the wheel base, 56″ and the engine number, Y8891
I spent nearly three hours on line last evening looking for tires and found none.
Any information is greatly appreciated.