Lee Anderson has been kicked out of the exclusive Carlton Club after he quit the Conservative Party.
The new Reform MP was sent a letter just a few hours after announcing he was defecting.
The swanky private members club is a second home for many Tories, who are given discounted membership.
In an email, its chairman Lord Young of Cookham, a Tory peer, wrote: “I am writing as Chairman of the Carlton Club to ask you to resign your membership.
“When you applied, you confirmed that you were a supporter of the Conservative Party. By joining a rival party, Reform, you are in contravention of that declaration.
“Should you not tender your resignation within seven days, the General Committee will take steps to expel you when it meets on March 26th.”
The former Tory deputy chairman was unveiled as Reform UK’s first MP at a hastily arranged press conference on Monday morning.
Mr Anderson lost the Tory whip last month after refusing to apologise for claiming “Islamists” had “got control” of London Mayor Sadiq Khan.
The Ashfield MP declared “all I want is my country back” as he stood alongside leader Richard Tice.
Mr Tice said his only MP is a “fantastic champion of the Red Wall” and boasted that Reform UK is going to “replace the Tories as the alternative” in the north and Midlands.
Reform UK honorary president Nigel Farage said Mr Anderson’s decision to defect is “huge”, warning: “I don’t think Westminster really understands this yet”.
