Video obtained by the Mandurah Coastal Times shows players drinking alcohol and dancing on a bench with members of the club’s hierarchy in attendance.
The Thunderbirds team has players aged from 14 to 17 years old.
Three concerned parents contacted the Mandurah Coastal Times after seeing the footage.
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READ NOWThey said the footage left them “horrified” and deeply worried about the club’s culture.
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Parents raised issues more than a week out from the grand final after hearing about an after-party being planned by the girls.
A parent said the Club’s coach sought clarification from the committee that no party would take place.
“I know a parent escalated concerns about the party to the coach of the team, I know the coach escalated that to the committee to say ‘look, I’m not aware of this party, are you aware because I don’t condone that sort of behaviour’,” they said.
“One of the committee members responded and said ‘no, no, that’s not going to happen, we don’t endorse anything like that – it won’t be proceeding’.”
However, on Sunday night after the premiership win some girls from the club attended a ‘private’ celebration at a committee member and parent’s house where the girls were drinking in club attire.
Peel Thunderbirds League coach Mark Fenton said the club could not control team members at a private function.
“This was not an official function endorsed by the club,” he said.
“We can’t control what people do at a private residence at private party.”
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Thunderbirds President Ann Fenton said the club did not condone underage drinking.
Three parents said they would not allow their daughter to play for the Thunderbirds next season due to the incident.
Mandurah Police officer in charge Stephen Thompson said police responded to an incident.
“No offences were detected and we’ve closed the matter,” he said.
“However alcohol and underage people are never a good mix and can lead to anti-social behaviour which is always concerning to police.”