I looked up the duties of Linesmen in the FA rules:-
Assistant referees
They indicate when:
- at penalty kicks, the goalkeeper moves off the goal line before the ball is kicked and if the ball crosses the line; if additional assistant referees have been appointed the assistant referee takes a position in line with the penalty mark
The assistant referee’s assistance also includes monitoring the substitution procedure.
The assistant referee may enter the field of play to help control the 9.15m (10 yards) distance.
I'm surprised they are supposed to indicate which team is entitled to take a throw in. Most games nowadays it seems the linesman puts his flag up then waits for the referee to indicate which way the throw should be taken. Is this a new unwritten rule or is it down to the referees/linesmen on the day? It seems to me linemen only draw attention to the ball going out of play - be it for throw in, goal kick or corner. They usually seem to indicate whether it should be a goal kick or corner but rarely give the decision for throw ins. They sometimes draw attention to foul play but seem to frequently miss blatant shirt pulling etc right in front of them.
Of course all refereeing would be much simpler if players didn't cheat. I'm tired of players going down, rolling around in apparent agony, screaming, holding a part of their body that hasn't been touched - then getting up a few seconds later and running around as though nothing has happened. Problem is that if the referee is weak, the perpetrators get away with it