The Public Carriage Office has no legislative power to investigate road traffic offences committed by cab drivers. I can only advise you that if you have a complaint about the driving behaviour of a cab driver you must report the matter in person to the nearest police station.
Incident:
http://www.londonfgss.com/thread1264.html
Report to PCO result:
http://www.londonfgss.com/post36559-57.html
The Public Carriage Office has no legislative power to investigate road traffic offences committed by cab drivers. I can only advise you that if you have a complaint about the driving behaviour of a cab driver you must report the matter in person to the nearest police station.