The first surprise was that the parents of the rival sides stood on opposite touchlines. I stood on "our" side while, during the first half, Gareth happened to be playing on the other side of the pitch.
"How's it going?" I asked him at half-time. "OK, Dad, but they keep swearing at me." "Who? The other players?" "No, the parents." Every time he got the ball, or tackled an opponent, he said, he was called "a little c-- -". The "f" word was also used frequently. It got worse. In the second half, one of my son's teammates committed a number of fouls. At the final whistle, the 18-year-old son of the rival team's coach ran on the pitch, swore at the 12-year-old boy, and threatened him with his fists. Luckily, the young man was restrained and the boy left the pitch unscathed.
Other matches passed without such incident, but dissent from referees' decisions was commonplace among the boys and even more so among the parents who, I was told, sometimes came to blows.
Some qualified referees won't touch boys' football. "It's not so much the boys as the parents," one Gravesend official told me. "School matches are not so bad, but a lot of referees steer well clear of boys' club matches."
Perhaps rugby parents are more "polite" because they are middle-class. Perhaps the fathers of football players see a future for their sons as million-pound-a-year Manchester United stars.
But, then, perhaps rugby is changing too. This season,Gareth went back to playing rugby at under-15 level. In the third match, a Gravesend boy was guilty of an unlawful high tackle. The opposing coach shaped up to him. There was an altercation. The match was abandoned.