Good Questions: Decoding the Q and A of letters in the mail

MORE de-bafflement for puzzled readers.

Is it my imagination, or do disproportionately many postcodes include the letter Q? (John Humbach, Brussels)

Probably the former, although no analysis of all 1.7 million postcodes in Britain has ever been conducted to prove it. The first half of the postcode, called the 'outward code', sends mail to the correct area and is generally based on the letters of a town or district, so we can probably assume that Q is infrequent there. The second half, the 'inward code', used for local sorting, is more interesting.

After the numerical part come the last two letters which may not include the letters C, I, K, M, O or V, excluded on grounds of clarity: I and O may be confused for numbers, and the other four letters (according to the Post Office) may, when hastily written, look like something else. The remaining 20 letters are used to divide the area into geographical regions, then sub-divide, generally into groups of 15 to 20 houses. When the codes were originally assigned, however, gaps were left to allow for growth. So sectors A, B, D (no C, remember) may be followed by F, leaving E for a possible tower-block. This applies to both the penultimate and final letters of the postcodes. Such decisions are made locally and have no necessary uniformity between different areas of the country.

To test Mr Humbach's Q-conjecture, we randomly selected 431 addresses from three telephone directories. An analysis of the 862 letters occurring at the end of the postcodes revealed 50 Qs compared with the 43.1 that would be expected by chance. Compared with P (69), J (64), A and D (62 each), however, Q had nothing to write home about. The area around Crewe seemed to be particularly Q- rich. The least common letter in our survey was G, with Y and Z not much better.

Why are prostitutes known as 'toms' by the police and the court system?

(Derek O'Sullivan, Camberwell, London)

The etymology of this expression seems to be a total mess, with two 19th-century roots wandering off in different directions before coming together again in the 1940s. We have the rhyming slang jam tart or raspberry tart for heart or sweetheart (which also seems to be the derivation of 'tart' for prostitute). When it reached Australia in the 1880s, there are records of jam tart, tam tart (perhaps a more alliterative version of the same) and tom tart, all meaning either sweetheart or prostitute. One source says of tom tart: 'not derogatory, but not used by women of themselves'. Partridge gives tom as a verb meaning: '(Of men) to coit with' - a North Country expression suggested by a tomcat's activities. To 'tom' later came to mean to work as a prostitute. Partridge also gives Tom (with a capital T) as meaning 'a masculine woman of the town' or a woman 'who does not care for the society of others than those of her own sex'.

Other sources add to the confusion by introducing a distinction between 'toms' (high-class streetwalkers) and 'edies' (prostitutes of the East End and railway stations), with no derivation offered for the latter.

With tom cats tomming around the streets, and raspberry, jam, tam and tom tarts travelling to Australia and back, the identification between tom and tart, at least in the vocabulary of the police, seems to have been finally established around 1945.

The OED also informs us that 'tom' is the knave of hearts in the game of gleek.