So sorry to hear this. I knew of Christian but not to speak to only really by recognising him and knowing who he was because we were at the same school where I was a couple of years older but my brother was in the same year as him. I saw him at Oxford games from time to time over the years.
My Dad started up Cumnor Minors again in the early 1980s after quite a few years without a team in the village (there was a mens team called Crawley Players that used the rec for matches occasionally but no junior sides), there was always a group of us down there playing football so when there seemed to be enough 8 year olds wanting to play from the village (plus 2 or 3 friends from Botley and North Hinksey) it made sense to see if it could work, my Dad took on the hard work and administration of running the team and club to get it started and registered, and the club grew from there. Colours in those days were gold and black with a green away kit (my Dad still has the old kits somewhere and diaries of the matches we played which included the first 11 that played and the subs plus who got man of the match), black shorts were chosen because that was the same colour as Matthew Arnold school kit shorts so you didn't have to buy another set of shorts making it more affordable. Christian would have been in one of the teams that was probably set up only a year or so after the original team when younger age groups naturally followed once the club had become more established and known about in the village and there was a desire for other age groups to follow.
It's so sad to hear this when it is someone that you knew from a long time ago from where I grew up, my condolences to all the family and friends of Christian.