What do the referee and marker do in English billiards?

• The referee shall: decide anything the rules do not cover in the interests of fair play, keep proper conduct, intervene on any infringement, tell a player the position of a ball and clean a ball on request.
• The referee shall not: answer questions the rules do not allow, warn a player that they are about to foul, give advice, or say what the difference in scores is.
• Questions allowed: whether the cue-ball is in the D, whether a ball is in baulk, whether balls are touching, and how many hazards, cannons or pots off a spot have been made.
• Evidence: a referee who missed an incident may ask the marker, other officials or spectators, or view a video.
• Marker: keeps the score on the board, helps the referee and may record strokes.
• Stroke recorder: records each stroke, the points, the breaks and any warnings.
• Timekeeper: runs the match clock where time matters.
• Help: holding a light out of the striker's way, and helping players with disabilities.
• No referee: the opposing player or side acts as referee.

The glossary has the referee, the marker, the timed session, the unsporting conduct, the limit on hazards and the limit on cannons.

Billiards depends on counts and positions that are hard for a player to keep track of in a long break: how many hazards, whether a ball is in baulk. The referee holds that information and gives it on request, but never advice, so that the player's own judgement decides the play.