Horse Immobiliser

Cold and windy out this morning. We walked along a path we haven't used for a while and came across this wonderful sign. Apparently this horse has been fitted with an anti-theft device (wonder if it is factory fitted)....

Anyway it amused me and it got my imagination going - does the device really stop the horse being stolen - i.e. will it refuse to start unless you have the key? I thought that was standard with horses anyway...

Would the horse start with a carrot or an apple or a polo mint?

Oh boy...it must be SillySaturday.