Two hardtops were originally available for the MGA. From 1956 the MG factory in Abingdon could supply you with a black, aluminium hardtop made by Vandenplas, a subsidiary of BMC. Later, with the introduction of the MGA 1600, the aluminium hardtop was replaced with a fibreglass one made by Universal Laminations, one that was obviously cheaper to produce. Apart from the material they were made from, they were also quite different, notably in the rear window area and in the way they were fixed to the body
the aluminium one as pictured in the Twin Cam Operation Manual AKD 879

fibreglass hardtop as shown in the MGA 1600 parts catalogue
There were other manufacturers who wanted a piece of the cake. Below the original Universal Laminations hardtop, on which Abingdon's GRP one was allegedly based. Note the internal roof light; a standard fitting on these tops


Other manufacturers were for example Plasticon Inc. in El Monte, California, who made a strong, lightweight, reinforced plastic hardtop.
And what about this Fibreglass Fastback from Custom Automotive. Looks sleek, doesn't it?
(advert from Road & Track, April 1960)

Italian hardtop made by M.M. Fattori & Montani. According to the advert the hardtop "follows smoothly the lines of the MGA, thus giving it a typical Italian appearance".
