HM

[[t]e͟ɪtʃ e̱m[/t]]

HM is the written abbreviation for Her or His Majesty or Her or His Majesty's. It is used as part of the name of some British government organizations, or as part of a person's title.

...HM the Queen.

...his enlistment in HM Armed Forces.

...HM Chief Inspector of Fire Services.