Nice find very interesting.
It is of course PlayPeople the big clue is in the number PP .
The set was shown in the marx toys catalogue 1978 in white set 1765, the stickers are genuine.
The Marx factory didn't make vehicles as far as I know, all where made in Germany and then sent over to the UK. As most of you know this helicopter was made in yellow for set 3247 the white one shown in the catalogue and collectors guide was a PlayPeople idea. I think the earliest Playmobil white helicopter of this type was in set 3144 of 1988 ten years later.
So the question is did someone buy 3247 and put PP stickers on it from 1765 or did Playmobil send over a load of yellow helicopters and use the old "colour of contents may vary" excuse when you opened 1765 and found a yellow helicopter in the box rather than the white one shown?