Free
The Arena (Colonel Russell series Book 3) by
William Haggard
First published in Great Britain in 1961 by Cassell
First time in ebook
I remember reading this series long ago
Colonel Russell of the Security Executive
The City of London is Britain's financial beating heart and a nest of gossip, intrigue and greed. The Government has always been powerless to control its activities. But when a sinister foreign company looks set to take over one of Britain's oldest banks, which in turn controls government secrets, Colonel Russell's Security Executive is faced with a dilemma - to watch, wait and let the free market operate, or to act and cross the invisible line into the Arena . . .
https://www.amazon.com/dp/B01H2DPLSI/
https://www.amazon.co.uk/dp/B01H2DPLSI/
https://www.amazon.ca/dp/B01H2DPLSI/
I have only checked the UK and Canadian availability
Also published NOT FREE
Slow Burner (Colonel Russell series Book 1) by William Haggard
Venetian Blind (Colonel Russell series Book 2) by William Haggard
The Unquiet Sleep (Colonel Russell series Book 4) by William Haggard