What it says really, a showing class for hunter types. They can be split in to small, ladies (traditionally shown sidesaddle), lightweight, middleweight and heavyweights. You will all ride together then do an individual show, showing walk, trot and canter on each rein and a good gallop up the long side. At local riding club level the judge rarely rides (in my experience anyway) but at some agricultural shows and definitely at county level you will also have to strip them down and they will be ridden by one of the judges. There is no jumping for a show hunter, the working hunters do that. Navy hat with flesh coloured harness, tweed jacket, shirt and tie for the rider, beige jodhpurs, long boots, gloves. Navy jacket and stock is only really acceptable for evening or championship performances. Plain brown tack for the horse, double bridle is a good idea, no martingales etc. Either no numnah or one that hardly shows. No pretty browbands, they are for the riding horses and hacks.
Here is a picture showing you gents and ladies turn out for local and County level showing. The class is middleweight, so horses to carry up to 14 1/2 stone all day across country. (this is my own picture and our own horse before anyone pushes a button). Both the chestnut and the bay are middles, the turnout will be the same for a small, light and heavy. Ladies will be side saddle and habit, navy or tweed. Make sure you have read the hat rules for wherever you plan to compete, they have changed several times and it is easy to get caught out with the wrong standards.
Horse turn out standard - local and county
Gentleman's evening or championship turnout at County level only. A lady will wear black.
School your horse really well, he/she needs to be balanced and well in front of the leg, be used to other riders and have excellent manners.