Hans Helweg was a Danish illustrator who is probably best remembered for the work he did illustrating Michael Bond’s series of books about a guinea pig named Olga da Polga.  For example:

However, before Hans Helweg brought Olga de Polga to adorable life, he illustrated several covers for Pan Books, a British paperback publisher.  In the 50s and 60s, Pan’s paperbacks was known for their colorful covers, which has since made them highly attractive to collectors.  Helweg was responsible for some of the most colorful.  And since Helweg, as opposed to many other illustrators, almost always singed his work, his covers are some of the most eagerly sought after.

Here are just a few of Han Helweg’s Pan Book covers: