In much the same way that you are entitled under British Law to take and be referred to by any name, you also have the right to determine and take your own title and salutation. Titles differ somewhat however as they are not considered to be part of your legal name for identification purposes. This is the reason the British Government does not issue passports showing the bearer’s social title.
You can include a change of title on your Deed Poll change of name declaration, if the change is to Mr, Mrs, Miss, Ms or Mx. Anyone can take and use these titles provided that they don’t do so for fraudulent reasons.
Mx as a Gender-Neutral or non-binary title
Mx is a relatively newly conceived title, used predominantly by those people who do not identify themselves as male or female. Mx is an alternative social title and may be used in place of Mr, Mrs, Miss or Ms.
The title meets a need for the growing number of people who aren't comfortable using gender specific titles. Whilst Mx is not the only gender-neutral title, it is the most widely used.
Most academic and educational titles are not considered to form part of your legal name and as such are not included on the name page of the holders passport.
Where HM Passport Office are satisfied that the holder has legitimate cause to use the title, they will include a note on the official observations page.
This is the case for holders of Doctorates and PhD's, Solicitors and Barristers apart except from members of the Queens Council.
Foreign and Presumed Titles
HM Passport Office does not recognise foreign diplomatic or noble titles as forming part of the holders official legal name, they do however, in the interest of diplomacy, recognise foreign titles on the official observations page of the passport.
Similarly, presumed titles, and Lordships of the manor (which are not a title in the sense of a true Lordship) are not considered to be legal titles for the purpose of forming your legal name. HM Passport Office have discretion when deciding whether or not these titles should be recorded as official observations.
Titles of Nobility
Whilst social titles are not considered part of your legal name, some titles of nobility are. If you have a title of nobility that is used as part of your legal name, Her Majesty's Passport Office will include it within the name field of your passport.
This applies to;
Members of the British Royal Family
Members of the House of Lords (including archbishops, bishops and the wives and families of members)
Baronets, holders of knighthoods and their spouses
Baronetesses and Dames.