In Scotland, girls can play mixed football until they are 15.
But Alyshia Walker, 13, captain and top scorer with the under-13 side Fauldhouse Foxes, was barred from playing in the home nations Tesco Cup in Birmingham yesterday because it took place south of the Border, where rules prevent girls playing as part of a boys' team if they are over 11.
The decision came despite a plea from Scotland's sports minister Shona Robison, who said: "Alyshia's talent is more than obvious, and with such a weight of opinion siding with her the FA could surely waive the rules."
The minister was backed by West Lothian's two women MSPs, Angela Constance and Fiona Hyslop.
The campaign also gained high-profile support from singer Rod Stewart, TV presenter Lorraine Kelly and former Scotland goalkeeper Jim Leighton, and was highlighted on The One Show on BBC1.
Scotland's national footballing body has said it might leave the competition next year following the decision, and more than 1,100 people have signed an online petition to try to get the English FA to change its rules.
The Bathgate Academy pupil scored more than 60 goals for her team this season in just over 20 games, and has earned national caps for Scotland at under-15 level.
Yesterday the girl, who had to hand over her captain's armband before the cup game, which her team lost 1-0 to England, said: "I feel really gutted. I didn't think the Football Association would change their mind, but I still kept hoping they would right up to the last minute.
"Every player should have a chance to show what they are capable of, and that's not happening for me today.
"I'm shocked and disgusted. I found out I wouldn't be allowed to play earlier this month, a week after the Scottish Cup Final. But I'm in Birmingham today to encourage the rest of the team and tell them to keep going."
Ina Meek, Fauldhouse Foxes' club secretary, said: "Tesco have told us they have tried everything they can about amending the rules for this game..
"But they haven't been very vocal about saying they appreciate our situation, and we think they could have done far more.
"We are really, really angry. We abide by the rules that govern Scotland, but suddenly it's just England's rules which apply when it's a four nations tournament."
David Little, national secretary of the Scottish Youth Football Association, said: "The English FA are putting a rule change up to their annual general meeting, but if the change does not go through for next season's competition, we will either not participate or we would ask that the tournament is held in Scotland."
A Tesco spokesperson said: "This tournament is played under English FA rules over which we have no influence."
No-one from the FA was available for comment.