I think it's bollocks and this is fairly local to me. I have a six year old boy and I don't believe a six year old boy wrote that. It's the sellotaping money to it (a six year old would just put the money in the envelope), the ripped paper, the envelope itself.... He didn't pay postage but where was it addressed to? You can't just put "Swindon town." Where did he get the envelope and the sellotape? How did he get to a postbox without his parents knowing? If his parents did know, why didn't they get him a decent bit of paper? Six year olds get universal free school dinners, so his mum isn't scrimping for change for dinners.
Sorry but I think it was a parent who wants free season tickets and trusted the power of social media