The author's name was Hugh Walters - a pen name, his real name was Walter Hughes - and the series of novels dealt with space exploration, starting with Blast Off At Woomera written in 1957, all the way up to The Dark Triangle in 1979. They were very simplistic, with basic science, and any schoolkid picking them up today would laugh his guts up (after getting an answer to the question "Mummy, what's a slide rule, and why don't the astronauts have a computer?") but I loved the adventure, and the mateship displayed by the closeknit group of astronauts.
So, next year when I venture back to Bookfest, I'm taking a list - and the six unknowns will be at the top.