Meaning of 007

In the USA after about 1870, it was relatively rare for a locomotive to bear an individual name, and each one had two numbers, its 'builder’s number' and its 'running number'. The former was for internal use by the company which built the locomotive, and was usually sequential from 1 onwards (in the case of the Baldwin Locomotive Works, America’s prime locomotive builder, the final locomotive built had a builder’s number of 70,541) It appeared on a ‘builder’s plate’, riveted to the locomotive structure in some comparatively inconspicuous place.

The 'running number', in both British and American practice carried in large numerals either on the tender or the cab side, was the number by which the locomotive was known in everyday talk: in the USA, this was usually prefaced by the definite article – a famous flyer of the New York Central, a 4-4-0 with the identifying number 999, was known as “the 999”. British practice saw many passenger locomotives given names (though very few locomotives for freight duties bore them).

The ORG commented that “to avoid confusion with any actual locomotive, [Kipling] took the unusual course of starting with two cyphers and not content with this prefixed them with the decimal point”. The ORG continues:
“Since the author was an educated Englishman writing in English, there is no need for controversy as to the pronunciation of the title, which he would naturally have given as “point (or decimal) nought nought seven”. Readers in countries where the nought is called “zero” (e.g. France and the USA) will no doubt pronounce it in that wise, but nowhere, it is hoped, except in the world of telephone operators, will “owe owe (or double-owe) seven” be employed.” The ORG was written before Ian Fleming’s James Bond, special agent 007, had made an impact, and it is feared that many, if not most, readers today would use “owe owe seven”