The insurer is run by former Lancashire chief Richard Brindle
Bermuda-based specialty insurer Fidelis will begin underwriting in the UK, after receiving PRA approval.
The insurer will write political, war and terrorist risk, as well as specialist marine and energy products.
It will be run by UK chief executive Dan Burrows, alongside chairman of specialty Nick Burkinshaw and specialty lines underwriter Richard Coulson.
The insurer is run by Richard Brindle, founder of UK-based insurer Lancashire, who said: “A London based business gives us the platform to build out our specialist insurance business.
“Under Dan’s leadership I am certain that we will rapidly establish ourselves as a new force within the London market.”