It is a truism that sergeant-majors on parade when calling troops to attention say anything but ‘Attention’: the varieties generally are ‘ten-shun’, ‘shun’, or more interestingly ‘hattention’. Why the intrusive ‘h’, and how does it connect to other intrusive ‘h’ usages?
Barbara Fennell (A History of the English Language, Blackwell, 2001) gives a useful survey of /h/-loss in the Middle English period and later; it began to disappear between 1300 and 1600, ‘hlaford’ becoming ‘lord’, and ‘hlafdige’ becoming ‘lady’, and was probably a middle-class unstigmatised speech change. However, by the eighteenth century ‘h’-loss was a sign of vulgar speech, and a phenomenon which excited some comment. John Walker in 1791 reserved particular disapprobation for the people of London who sank their ‘h’s; by this time a clear class distinction had been associated to the usage, so much so that middle-class speakers strove to avoid it. This would certainly explain the class-aware intrusive ‘h’ in sentences such as /Hay thank you/, characterised as posh English used by the socially aspiring, a mid-twentieth century phenomenon now more or less obsolete.
Early-twentieth century music-hall comperes and mid-twentieth century bus conductors were also characterised as using intrusive ‘h’s at the beginning of sentences, most likely intended for emphasis in noisy environments; in both cases there may have been an ironic self-aware class-identification, a ‘listen to me’ aspect to the deliberate pronunciation with social class aspirations, pitching the speaker as having some authority, which would link to the sergeant-major on parade. All three, bus-conductor, music hall chairman, and sergeant-major, would often have been near the edges of the social class Walker eyes, ‘the people of London [who have the habit of] sinking the h at the beginning of words where it ought to be sounded and of sounding it, either where it is not seen, or where it ought to be sunk. Thus we not infrequently hear, especially among children, heart pronounced art, and arm, harm.’ Walker’s influence on ideas of acceptable pronunciation was strong throughout the nineteenth century and into the twentieth; certainly ‘h’-loss was stigmatised until fairly recently, and still characterised as typical of London or estuary accents. The compensatory class associations of ‘Ha-ten-shun’ remain complex.
John Walker, A Critical Pronouncing Dictionary and Expositor of the English Language, 1791