The very first horse trailer, so it's said, was built to transport a single horse and was pulled by six horses. That might have a pointless feel to it, but if the story is true then the horse being taken by his six equine mates won a lot of money through being transported in this way to Doncaster.
It's a neat story, summarised HERE.
Jack himself rarely travels by any means other than hoof, but there was one significant journey detailed HERE.