Many organisations no longer give out email addresses. (It's a security measure to prevent attacks on their web servers and to prevent spamming of their email accounts). Instead they use web forms, which serve exactly the same purpose anyway. (i.e. the sender's message ends up in the email inbox of the intended recipient).
That seems to be the route that Princess Royal Hospital League of Friends has gone down. If you use this web form, your message will arrive as an email in the inbox of their treasurer, Andrew Fox, who will then forward it if necessary:
https://www.prhfriends.org/contact-us