Ran across this while browsing a little bookshop this afternoon. It's a 1955 UK edition that seems to be part of The Challenge Series For Boys and Girls from The Children's Press of London and Glasgow.
This is one of the original titles the series apparently mixed in with reprints of classics such as The Swiss Family Robinson.
The book style resembles Western Publishing editions from the U.S., though it's slightly smaller in size than those.
I paid $5 for it.