“Until the early nineties, I was under the impression that the Celts were this mad collection of anarchists from Ireland, Scotland and Wales. When I saw an exhibition in Venice, I discovered they were a vast collection of tribes originating from Middle and Eastern Europe as far back as 500 BC, and that over the centuries they migrated and integrated with people all over the world. So I've used this cultural history as a creative muse. With The Book Of Secrets in particular, I was interested in beginning with their earlier and more Eastern history”