I’m browsing banks for a new savings account, and I found this on the Skipton Building Society application form. I have no idea if other banks do this, but I find it pleasing that the title ‘Mx’ is available on their form:
More info on gender-neutral titles is available here. I find it really interesting that in the UK, the only non-gendered honorifics are related to occupation or level of qualification. But we still get that wrong, sometimes. Oops.