According to London journalist Angus Watson, in a postscript to his debut novel Age of Iron (Orbit, £8.99), “almost nothing” is known about Britain’s Iron Age.

This virtually blank canvas has allowed Watson, a fan of both historical fiction and epic fantasy, to let his well-read imagination run freely within pretty broad parameters.

The result is a southern Britain which, in 61 BC, knows that the all-conquering Romans are on their way. Many argue that resistance is futile, while others insist that a united island could see off the imperialists. Some are preparing to welcome the invaders, believing they’ll bring with them a modern, technological life of leisure and plenty.