Certainly not "politically correct" by today's standards but fiendish plots are exposed and the arch villains are dealt with in a satisfying manner. It reminded me of Dick Barton! Fascinating insights into the concerns of the times - from a communist. takeover after World War 1 to the possibility of a future second world war in the late 1930s. The complete collection is incredible value for money.
For me, in my imagination, Slider looks like Frost. Atherton looks like Hatherway. If you love Frost and Lewis on TV then I think these books are for you. I find the characters, locations and storyline are all utterly convincing.