Same thing happens at all major sports events where there is large scale betting interest. At the Open Golf you will see a reporter feeding back info on every shot from the contenders and well backed golfers. I’m guessing the reporter is shared by all the major companies who bet on the winner in running. I worked for William Hill in the 80’s, sometimes at the North West Head Office was in Wellington Street, Stockport. The shops had a liability table. Any single bet taking out more than £200 had to be approved over the phone from Stockport. However, if it was on for example on Miss World and the bet was from a “stranger” it had to be rang in if the stake was over £10. Big winning bets also needed to be checked and verified by HO. One night a dual forecast patent on GRA greyhounds came in for about £300 to a 70p stake. The problem was the same bet had been placed in several shops around the country by “strangers”. The bets were cancelled and the punters lost out. It also happened with more publicity to the 100/1 hole in one betting and Flockton Grey’s infamous 2 year old race (he was actually 3 years old at the time).At the derby a few seasons back there was a guy sat behind me talking on his phone all match. I thought he was a rag at first but he was giving a running commentary on the game with code based on which team had the ball and how close they were to scoring. So if the ball was in midfield with City in possession he would say something like 'blue one', and then 'blue two' if we moved into their half. I remember United scoring and he was shouting 'red five' as the shot was taken and 'goal red' as the ball went over the line. I'm guessing he was on his phone to a mate trying to get an edge on the in-play market, by removing the few second broadcast delay?