Ok, I have received this Yeelow Mushroom smurf. The top is indeed yellow with a blotch of slight orange discollouration - the underside of the mushroom is light orange almost yellow. the mushroom stalk is painted yellow.
On the underside of the feet is "W. Berrie & co.", "Schliech" "Made in Hong Kong", Copyright 1979 PEYO" and number "2".
Sorry, delirious Karen because accounts nearly finished, husband wants to know why even though he keeps walking sideways through tunnels he hasn't got to Bangkok yet.