Police Standard Operating Procedures have recently changed in London - These require all mentally unwell people who have been sectioned to be transported to a place of safety in an ambulance. Only the most violent people should be put in a caged police van. I think this is so that the patient is with healthcare professionals who can watch more closely for dangers like positional asphyxia. Of course the media and public interest with 'deaths in custody' have had a major impact on this policy change. You may just feel like a glorified taxi but your skills could come in very useful during this period.