I'm thinking this bike came in pieces, looked the right bits, but it is not what you hoped for.
For those in a similar situation....
Early frame uses a solid swing arm spindle and so called small bore bushes 42- 4115. Solid spindle for these is 42 4112. The frame holes match the spindle diameter. Rear brake is rod, left hand side brake drum/sprocket. On an unmolested frame there should be provision to mount the brake pedal pivot.
Later design...'56 onwards uses the crossover brake shaft, the bushes used 42 4362 have a bigger bore, 13/16" which is the size of the hollow spindle (42 4340) O.D. and the matching holes in the frame.
So for the bike in question, how you proceed really depends on what you have. If the S/A is fitted, has a good set of bushes and a solid spindle, stick with this original QD design. I'd ditch the Ariel rear wheel, the earlier single sided brake is better, and the QD hub is a far better prospect. Changing the S/A bushes is a black art, avoid it if you can. Solid spindle narrow bore bushes have a greater amount of rubber, less prone to failure. Very thin rubber insert on the later bushes is subject to more torsional strain. Could be the S/A and matching wheel are the later type, look the part, but are not the right components for the frame. Of course, if the frame cheeks are worn, then providing the frame holes can be enlarged with the same precision as original, the later S/A hollow shaft and bushes could be substituted, as always assuming the Ariel wheel matches the fixing lugs.
Sourcing the bits is the biggest stumbling block, but the information you need is in the Forum Literature section. Also there are plenty of topics relating to problems folks have had with this theoretically simple suspension design.
All models use the same diameter fork stanchions, fork ends can be chosen to suit wheel type and mudguard mounting. As recommended Draganfly's online catalogue tells it all.
Welcome along, send us some pictures, we love 'em!!
Swarfy.