Oxfam UK is currently heavily promoting its Pride Collection of goods, instore and online. It explains why:
https://www.oxfam.org.uk/about-us/lgbtqia-rights-are-human-rights/
What I hadn't previously spotted is their 2021 statement on trans. Its links to 'incredible organisations to follow' includes Mermaids and the Tavistock Clinic.
https://www.oxfam.org.uk/oxfam-in-action/oxfam-blog/happy-international-day-of-transgender-visibility-resources-for-your-inclusive-journey/
I'm going to write to their Supporter Relations Team, explaining why they have lost my support with this. But wanted to open up the conversation here first, as it may shape what I write.