Two comments rarely made by a dressage judge in the same sentence.

"Very behind the vertical yet lovely and light in front"

If I had a pound for every time I judged a horse that was behind the vertical and on the forehand I'd be a rich man!!

Young horses need time for the withers to catch up with the quarters and until they do it's hard for them not to be on the forehand. Some fully grown horses are simply built 'down hill' and struggle to achieve proper balance even with good schooling so in walk, trot and canter they likely to be on the forehand. 

In order to get the horse 'on the bit' and 'elastic to the contact' a degree of flexion is required and the result is often that he becomes 'behind the vertical'.  This is one of the reasons why us judges are asked to be more lenient when judging horses at the lower levels that are on the forehand and/or behind the vertical. Instead we should be looking for a supple roundness with energy and rhythmical and flowing regularity.

This horse is proving that it's possible to be both light in front and yet behind the vertical at the same time - he's simply showing off to prove a point to us judges!!!  His owner recognises he is a unique individual and is looking into Hack Up Bespoke supplements as his requirements will be unique too.