Someone to share my competition horse with

I am looking for a competent rider to share my lovely black warmblood gelding with. He is around 17hh, a very sweet temperament with good paces and has won at the Addington Regionals and twice at the Nationals. He competes up to and including PSG but will happily do the lower levels.
He travels very well and is a gentleman to do in all ways. He is extremely supple and I have his back done every three months and he is shod by Matt Burrows at the Three Counties Vets every six weeks. He hacks alone and in company and is a total gentleman with other horses. I want him to stay at the same yard in Pembridge where he is very happy and there are good facilities and hacking.
In return for sharing costs, you would get the use of my lorry and be able to take him to competitions whenever you want and for training to whoever you want. You would be able to ride him up to four times a week. He is a schoolmaster but you need to be competent and to be able to ride to at least medium/advanced medium standard. And you need to not be overweight or unfit.