A-level Tudor history quick question

earl of oxford was John de Vere,
john morton was archbishop of Canterbury i believe,

Hello,
I'm just doing a Seneca course of The Tudors: England 1485-1603 about Henry VII and Seneca has written a sentence really weird. Seneca says: "Margaret Beaufort, Jasper Tudor, the Earl of Oxford, John Morton and Richard Fox were his closest confidants."

Is the Earl of Oxford John Morton or is it just referring to a different person? Is the sentence referring to 5 people or 4 people? Basically who was the Earl of Oxford during the reign of Henry VII?
Thanks in advance.

Just did a quick Google because I'm unfamiliar with this part of The Tudors. The Earl of Oxford during Henry VII's reign was John de Vere (13th Earl of Oxford). I agree that Seneca has worded the sentence poorly which isn't helpful.