I would not call the last 6 boxes Portugal-boxes. They are still the same UK boxes. The only difference is that the boxes made after summer 1981, starting with the go-cart sold in october 1981, got this marking inside the box. It is because the company Solito made these boxes for Maia. Actually the fireman and photographer also have the solito-marking, but then without Maia and Portugal.
You can see the same type on differences on the W Berrie-boxes, sometimes printed in W Germany and sometimes printed in Hongkong, still I would call them US boxes made for W Berrie. ??
In many of the UK-boxes you will find yellow dot-smurfs and special variation accessories. But not all are marked Portugal. The reason for this is that the Portugal marking did not start until later. In the beginning german-made smurfs just painted in Portugal were used. In the very early beginning I don´t think they even painted them in Portugal. Since then you could get both german and hongkong-smurfs also in the UK. But from around 1979 the smurfs mainly were painted in Portugal.
If you check the Maia Borges catalogue from 1985 you will find many supersmurfs and these were also sold in the UK boxes but then with a Maia Borges sticker. And then also sometimes with Portugal markings.
I think there are threads about this??? At least you can some information in the posts I made earlier about supersmurf-variations, eventhough alot of the information needs to be updated!!??