He acts as if to start to rush out, then faces his son.

John sees his father's face for the first time convulsed with fury.
"Do you know that man ?" he demands.
"Certainly." "Is his name Blunt ?" "Yes, sir." "I thought I could not be mistaken.

There is something singular that brings him here at this time.

John, is this Reginald Blunt a particular friend of yours ?" "Why, no, sir, in fact, he was my rival for the hand of Ruth Stanhope.
But you call him Reginald; this is Sir Lionel Blunt, a colonel from India and the south of Africa." "Then I made a mistake.

It is his cousin.