Drivng east down the M4 this afternoon I was passed by an apparently unmarked silver X5 with flashing blue lights, followed by an ambulance also with flashing blues.
Police escort with an unmarked car sounds a bit pointless, what would the X5 have been?
The likely scenario is that both police and ambulance attended the same incident - eg serious assault, bad RTC - and were on their way together to the hospital. So not a police escort, just both going to the same place.