Martin Aitchison has just released another 9 pieces of original 1970s Peter and Jane artwork for sale on his website. You can see them here:
There are some really great one there.

Also I have made a small clip about the earliest ever Ladybird Books (that is, the earliest books from the 401 series when Ladybird began to publish pocket-sized books). You can find it on the ‘Gallery page’.