The Women’s Institute will no longer accept transgender women as members from April following the UK supreme court ruling on the legal definition of a woman, the Guardian can reveal.

Melissa Green, the chief executive of the National Federation of Women’s Institutes, said the organisation had taken the decision with the “utmost regret and sadness”, adding it had “no choice” but to exclude trans women from its membership.

“Incredibly sadly, we will have to restrict our membership on the basis of biological sex from April next year,” Green said. “But the message we really want to get across is that it remains our firm belief that transgender women are women, and that doesn’t change.”

Membership of the 110-year-old organisation will be restricted to those who are registered female at birth

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