PowerSwitch

The relatively new Diamond jubilee carriage is reportedly air conditioned, I wonder how this is achieved ?

One possibility would be a more a less standard electric air conditioning unit supplied from a large battery. A 10 kwh battery could supply a powerful air conditioner for some hours, and the battery could be charged in a few hours from any standard outlet. Drawbacks include the bulk and weight of the equipment, and that the heat produced would be uncomfortable for the horses and nearby persons.

Another approach would be to use ice. Say 100 kilos of ice cubes stored in an insulated container could cool air that is blown through ducts in the ice container. No heat to get rid of, just a very small amount of condensation that could be dumped on the road without any problems. A very small battery could supply the fan, dry cells would serve.

A third option would be an ice bank that is frozen in place by an on-board compressor, mains powered when the vehicle is stored.

I have heard it was made in Australia.

Yes, it was a gift from Australia to the late Queen, very traditional in appearance but somewhat more practical than the gold state coach. I hope that our new King will use it regularly for the state opening of parliament and other special occasions.