Unknown piston set

[A G Wood]

They may be aftermarket replacements, although there would surely be trademark issues? According to Oldhams Press 'Practical Automobile Engineering Illustrated' (circa 1955): "the practice of replacing aluminium pistons by cast iron ones on light commercial vans or travellers' cars is  sometimes adopted. This is done with a view to obtaining a much greater mileage, not possible with aluminium pistons, before cylinder reconditioning is again necessary..."