Who is Antonio Silva from A Dangerous Fortune and what is their importance?

Tonio is also from Cordova and attended Windfield School. He was also present at the quarry pool the day that Peter Middleton drowned. He also remained in London rather than return to Cordova and works as an attaché to the Cordovan Minister. He dates April Tilsley who is Maisie's roommate. When David Middleton begins to ask questions about his brother's death, Tonio becomes a danger to Micky and Edward because he was a witness.