Every year there's a youngest ever referee, Michael Oliver has been youngest a couple of times. Youngest in the Premier League, youngest ref at Wembley etc. His father Clive was also a referee.
Micheal Oliver started his international career as a UEFA category 2 referee.
Oliver took charge of a couple of matches in the Europa League 2012, 2013 and 2014, as well as qualifiers in the Champions League and WC 2014 qualifiers. His star is rising slowly, so far his highest merit must have been the refereeing of the 2014 FA Community Shield between Arsenal and Manchester City.