Thanks Steve!
For me that sounds very correct. As far as I know National Benzole was a part of BP then and in UK they slowly changed the National stations to BP during the 80s. But I believe only National sold smurfs between 1978 and 1980 in the UK. It is only the boxes made early among the UK boxes which has National written on the boxes.
I think except from the early ones sold in Holland, BP then had them sold in South Africa, until around 1980??? Then in Australia and New Zealand between 1979 and 1981. I don´t think BP still had the trademark-rights for the word smurf in Australia in 1982. So therefore this playset was sold just before they stopped with the BP-smurf-promotion and that also explains why it is among the rarest Schleich box and playset you can find.
So if I would guess this BP playset could only have been sold in Australia and maybe New Zealand.
Steve, when National stopped selling smurfs in 1980 where could you buy them after that?? In the toystores??
Another thing. The rugby-smurfs sold in UK. How were they marked when sold in bags?? I know the ones sold in South Africa had the BP logo on them.