This is possible one of the best ones you can get (probably because it was actually recorded on my phone from a South Yorkshire Police Peugeot 308 in Doncaster, probably THE most authentic recording you can get.
Press H for the horn Click the 999/ABS button to activate/deactivate the blues. Whilst sirens are active, press H, and then H again within 0.7 seconds to turn off the siren