We know "Stim" or "Murdock" was Murdock Stimpson a comic artist, funny postcard illustrator -and illustrator of childrens (non-comic) books.
He was active from the 1920s to 1950s according to comics authority Alan Clark. However, there are (like many others) no known photographs of Stimpson and we do not even know when he was born or in what year he died.
I have seen "comic experts" list "The Mighty Atom" as one of the lost British super hero strips of the 1940s -even that it might be an American comic strip re-titled by Gerald Swan.
Always remember: "X" =The Unknown and "Spurt" is a drip under pressure.