Sir Henry Sidney, Philip's father, and president of the Council of Wales and the Marches, gave Greville in 1576 a post connected with the court of the Welsh Marches, but Greville resigned it in 1577 to go to attend court of Queen Elizabeth along with Philip Sidney.
En 1576, Sir Henry Sidney, el padre de Philip y el presidente del Council of Wales and the Marches, nombró a Greville en un puesto relacionado con la Corte de las Welsh Marches.