The big craze from this source [television] in 1966 was for a Batman outfit. This consisted of a large black cape, shaped cowl and pants with belt, with 'shimmering P.V.C. contrasting bat decorations'. So for 29s. 6d. a child was disguised and pictured himself flying over the treetops and in fact, with slit eyes and a nose-piece, a child did not look himself at all, and knew that his appearance was frightening.
Source: wiktionary