Several Peter May titles have dropped to £0.99 at Kindle UK, including the complete Lewis trilogy.
The Blackhouse, Lewis #1:
https://www.amazon.co.uk/dp/B004MYF4SS
The Lewis Man, Lewis #2:
https://www.amazon.co.uk/dp/B01LTA7K7A
The Chessmen, Lewis #3:
https://www.amazon.co.uk/dp/B0093LRP0K
Extraordinary People, Enzo Macleod #1:
https://www.amazon.co.uk/dp/B00CUE0CX4
Coffin Road:
https://www.amazon.co.uk/dp/B012DVZSP0
I'll Keep You Safe:
https://www.amazon.co.uk/Ill-Keep-Yo...dp/B0743GG64T/