Lonelyheart 4122 is the fourth in the Inspector Purbright/Flaxborough series by Colin Watson. It has dropped to £0.99 at Kindle UK.
Buy at Kindle UK
I also note two other titles in this series are semi-long-term at $0.99/£0.99 in the US/UK – the first, which is always kind of nice if you want to try the series out, and the last, which is good, I guess, if you make it all the way through ?!
Coffin, Scarcely Used, #1
Buy at Kindle US | Kindle UK
Whatever’s Been Going on at Mumblesby?, #12
Buy at Kindle US | Kindle UK
Lonelyheart 4122 is now $0.99 at Kindle and Kobo US as well, and it’s discountable at Kobo…
Kindle US: https://www.amazon.com/dp/B07B9MV35J
Kobo US: https://www.kobo.com/us/en/ebook/lonelyheart-4122-2