Ling rose quickly through the ranks as a referee. He was initially on the supplementary list as a Football League match official but even so was selected to participate in the 1948 Olympic Gamesfootball tournament along with George Reader, Stanley Boardman and A. C. Williams from Brighton. Ling refereed both the first round match involving Sweden, the quarter-final involving Italy and was then selected for the final between Sweden and Yugoslavia. The final itself turned on two penalty decisions early in the second half and which affected their temperament. Bernard Joy, in the 1960 publication "Association Football", wrote: "The setbacks rattled the Yugoslavs, their behaviour got out of hand for a spell and they did not recover their rhythm. What made matters worse was when Gunnar Gren converted a penalty midway through the second half. It is true that Gunnar Nordahl was bowled over, but the offence looked no worse than those committed by the Swedish centre halfBertil Nordahl."
By the start of the next season Ling had become a Football League referee, and within 3 years had been appointed to control an FA CupFinal. Ling refereed the FA Cup Final in 1951, in which Newcastle United beat Blackpool with two Jackie Milburn goals. On the day of the Final, Ling spotted a policeman as he arrived at Wembley Stadium. He recognised him as a player he had sent off previously during a Sunday league fixture and as he passed him, said: "Now what do you think?" The officer replied: "I still think you are no f*****g good!"
Ling's part in the final, between Hungary and West Germany, became slightly controversial because he accepted Griffith's offside flag in the final minutes to deny Ferenc Puskás a 3-3 equalizer could have sent the game into extra-time. West German radio reporter Herbert Zimmermann had called Puskás offside well before he kicked. Willy Meisl observed, later, that it appeared that goal keeper Gyula Grosics had struck Ling following the final whistle. Nothing came of this incident and the mood amongst the Hungarians had settled when the trophy was handed to the West Germans.
The final match itself became the subject of a German film Miracle of Bern in which the story of the match is told. Joachim Floryszak, a non-League German football referee and civil servant, starred as Ling after contacting the director Sönke Wortmann begging to be given a place in the film.
