Salisbury Plain is known for it's coursers, most are known by the relevent authorities, Police, Land Wardens, MOD Police etc.
Even if they are caught, which isn't very often, most get away with it through lack of evidence, that is if they even get past the CPS.
A keeper I know tackled some a few years ago and ended up with his windscreen smashed at the time and his wifes bicycle, which was outside his house, smashed up.
I think the bicycle thing was just to let him know they knew where he lived.
Nothing ever became of it.