Writer and actor Mark Gatiss, academic Hannah Dawson and human rights barrister Geoffrey Robertson are among those giving their views on the life and death of Charles I, who ruled England, Scotland and Ireland for more than 20 years in the 17th century. The king was put on trial for treason in January 1649 in an unprecedented attempt to try the institution of the monarchy as well as Charles himself, who was found guilty of treason and executed.