Bernard Cornwall's
Redcoat is just £0.99 at Amazon UK just now:
https://www.amazon.co.uk/Redcoat-Ber.../dp/B002RI9BIK
This is a stand-alone set in Philadelphia in 1777.
Also £0.99 is
Straight by Dick Francis, first published in 1989.
https://www.amazon.co.uk/Straight-Fr...dp/B002RI95IQ/
The First Rumpole Omnibus by John Mortimer is £1.99 (a repeat offer):
https://www.amazon.co.uk/First-Rumpo.../dp/B002XHNOEC
Flying Too High by Kerry Greenwood is the second in her Miss Phryne Fisher series, set in 1920s Australia. Only £0.99 at the moment:
https://www.amazon.co.uk/Flying-Too-...dp/B00841706Y/ (This is the first time I've found this one on offer.)