Barbara Cleverly (English writer) writes about the early C20th. Some novels set in Raj India, some in London, a couple in France and Greece. Really likeable (and fit!!) hero called Joe Sandilands, no sex or swearing, suitable for all age groups. Proper whodunnits with interesting motives. And really well researched (perfect for pedants like me!)
And several are currently 99p in the Kindle Store