Ian Blanchard, the Senior National Game Referee Manager, says that even one assault a season is too many and they have a comprehensive support system in place for any referee who has been attacked.

BBC: Rise in attacks on grassroots football referees

The leader of the Russian republic of Chechnya has apologised for using a stadium public address system to insult a football referee during a match.

BBC: Chechen leader Kadyrov sorry for stadium PA outburst

Like the Hawk-Eye system it uses a computer to send a signal to the referee's watch when a goal is scored.

CNN: Does football need technology?

However, it has added a further element to the referee's pre-match ritual with officials now needing to test the system 90 minutes before every match to determine whether the technology is working as expected.

CNN: World football enters technological era

The system involves an extra official standing on the side of each goal assisting the referee and two touchline assistants by communicating through headsets.

BBC: Uefa trials new refereeing system

If the system detects that the ball has crossed the goal line a central computer transmits a signal to the referee via either a watch or earpiece.

CNN: Does football need technology?