The little gentleman in black velvet is a mole. William III of England, II of Scotland (William of Orange) died of complications following a horse riding accident in which, it was believed, his horse stumbled over a mole's burrow. Following this, Jacobites would toast the health of the "little gentleman in black velvet" who brought about the death of their enemy.
а еще, по этому сайту translate.academic.ru/gentleman/en/ru/1
gentleman of the pad, gentleman of the road - «рыцарь с большой дороги», разбойник
gentleman of fortune - рыцарь фортуны; пират; авантюрист; искатель приключений
walking gentleman - театр. статист
a gentleman's gentleman - камердинер, слуга, лакей
old gentleman, gentleman in black - сатана, дьявол
gentleman in brown - клоп