Tree log legal issues

By law do you need any warning sign or lights on the back of logs that sre six feet longer than the trailer.
I saw a recovery truck go up the back end of a logger truck and the cab and steering wheel pushed back four feet with a lady and kid as a passenger near Wimborne Dorset and the driver was not hurt.
The big boss of the police told me they would measure the load too.
What is the legal length with logs?
What will happen to the log driver.Is he in trouble or not?