Verger - puzzling puzzle

A very bright and sunny Day The Priest did to the Verger say: "Last Monday met I strangers three None of which were known to Thee. I ask'd Them of Their Age combin'd which amounted twice to Thine! A Riddle now will I give Thee: Tell Me what Their Ages be!" So the Verger ask'd the Priest: "Give to Me a Clue at least!" "Keep Thy Mind and Ears awake, And see what Thou of this can make. Their Ages multiplied make plenty, Fifty and Ten Dozens Twenty."

The Verger had a sleepless Night To try to get Their Ages right. "I almost found the Answer right. Please shed on it a little Light." "A little Clue I give to Thee, I'm older than all Strangers three." After but a little While The Verger answered with a Smile: "Inside my Head has rung a Bell. Now I know the answer well!"

Now, the question is:

How old is the PRIEST??