Andrew, the ones you posted a picture of in the lost HJ mirror thread were offset mounting but they are one tonner mirrors. The standard HJ offset mount mirrors are standard on HJ Sandman... the centre mounted drivers side mirror as on the green Sandman in the brochure is an optional extra.

You will know if you had the cable remote mirror optioned on your Sandman as there will be 3/4 inch hole in the door where the mirror mounts and also a 3/4 inch hole in your door trim above the window winder with corresponding hole in the door inner panel. Very few if any Sandmans would have had these factory fitted.