When I bought my lowlight it was fitted with wipers that attached to the arms with a screw. It was going for MOT on Friday and Stevey noticed that the drivers side blade was breaking up so I fitted a pair of arms and blades with the rubber peg to hold it in place. What type would it have had originally? This car also only came with one wiper fitted as it has the older type of wheelbox that is screwed to the body below the rubber on the drivers side and a later series 11 tpe that can be more easlily removed on the passenger side.
The original Series MM had a single blade (home market). There was a conversion kit for two blades, drill holes and use the long rack and other parts. Workshop Manual Sect. N11
The Series MM blades are held in place by rubber pegs