If any vehicle obstructs their progress whilst on the way to an emergency call, it seems likely that the ambulance will be required to stop and obtain sufficient details of the vehicle and its driver in order to comply with PACE requirements necessary to allow the CPS to prosecute the driver of the other vehicle for obstructing the free passage of a vehicle being used for ambulance purposes whilst on an emergency call. Well, that's one way of reading page 34 of the Goverment's new Respect Action Plan (http://news.bbc.co.uk/1/shared/bsp/hi/pdfs/10_01_06_respect.pdf) "...we are currently looking at creating a new offence of obstructing the progress of ambulance workers, when they are responding to emergencies."