As of 2025, the UK does not issue passports with an X gender marker for non-binary people. UK passports currently use M (male) or F (female) gender markers only. This means that non-binary people cannot currently obtain a passport in the UK that reflects a non-binary gender identity in the gender field, regardless of what name they hold or whether they have a deed poll. This is a policy position that has been subject to legal challenges and ongoing debate; the situation may change, but as of now the binary-only policy applies.
What a deed poll can do is change the name on your passport to any name you choose, including a gender-neutral name such as Alex, River, Rowan, or any other. Your name on your passport is entirely separate from your gender marker. You can hold a passport in a gender-neutral name while the gender marker remains M or F. To apply for a passport in your new name, you submit your deed poll with a standard passport application in the usual way.
Some non-binary people choose to use their deed poll to take a gender-neutral name, request the title Mx rather than Mr, Mrs, or Ms, and leave the gender marker as it stands, changing what they can and noting where the current policy limits them. For trans and non-binary people who are also applying for a Gender Recognition Certificate (GRC), a GRC enables a change of gender marker on a passport (to M or F, not X). The EHRC and GIRES publish up-to-date guidance on current policy, and organisations like Stonewall track legal developments on the X marker question.