Agostino Carlini; Francesco Bartolozzi; Giovanni Battista Cipriani, 1777, by John Francis Rigaud. Three Italian-born artists who made their careers in England and who were all founder-members of the Royal Academy. Carlini is shown with a sculptor's hammer, Bartolozzi with an engraver's burin, and Cipriani, sitting before the easel, has a palette and a brush in his hand.
The Countess of Sussex by Paulus Van Somer (1576/78-1622) a Flemish artist who arrived in England from Antwerp during the reign of King James I of England and became one of the leading painters of the royal court. Which countess of Suffolk this is, I don't know, could be Bridget Morison, wife of Robert Radcliffe, the 5th earl. (His mother was Elizabeth Howard, the half-sister of the Elizabeth Howard who was Anne Boleyn's mother.)