This is the altar in the basement of Tyburn Convent that includes a replica of the Triple Tree, which during the persecution of Catholics under Elizabeth I, stood in the middle of the crossroad in Tyburn Village on the outskirts of London. It was the gallows from which many Catholic Martyrs were hung drawn and quartered. The site of the martyrdoms is now concealed within a traffic island, but if you know what you are doing, you can find it.