An exact date of first printing is unknown, as the earlier copy of Big Snake Hunters doesn't have a printing or copyright date inside. Only two Don Sturdy titles were printed in Britain (the other being The Desert of Mystery).
The text states that the exact printing date of "Big Snake Hunters" is unknown because the earliest edition doesn't have a printing or copyright date listed.  It also mentions that only two books by Don Sturdy were published in Britain, with "The Desert of Mystery" being the other one.