IMHO it is silly to use names of racehorses.
Whatever, for the record, I thought the A3s (and A2s, but we didn't see so many of those) were and still are, for the most part, fabulously ethereal, romantic sounding names. The very randomness - Captain Cuttle, Kinght of Thistle, St Gatien, Sansovino, Gay Crusader, Bayardo - meant they were all just so magical, so awe inspiring. They send tingles up my spine even now. I think the only other names to come near were the King Arthurs and the Dxx Walter Scott novel ones, but I saw none of those.
As with so very much in subjects of one's personal "fancy": it comes down to personal opinion / sentiment and "de gustibus" -- nobody's objectively right or wrong ! I'm very much with
@70014IronDuke on this particular question -- as I think I've made clear in this thread, I love the whole thing of racehorse names for locos, finding in it an element of mad, surreal poetry; but others feel otherwise -- and total freedom of opinion, "as should be".
The choice of name series was as often as not at the personal whim of the Chairman or General Manager so if one or both was a racing man it is easy to see how they might choose racehorse names. Similarly with Hunts and Football Clubs.
So, nomenclature pretty randomly at the whim of what avocations the Big Cheese happened to be "into". To me, seen in one light, a rather charming way of things -- even if liable to result in whole classes with names which did nothing for me (but would likely delight others). A considerable part of me, though, finds the whole organised-thematic-naming-of-locos -- including steam locos -- "malarkey", a rather foolish and pointless exercise: think I'm right in saying that for well over a century, it has been chiefly a British and Irish thing -- big railway undertakings elsewhere in the world mostly ceased long ago, to do it, except on a small, often individual scale for publicity purposes. In the earlier decades of railways, locos were named in profusion and with wonderful randomness -- that, I feel, would have been delightful and worth having; but precisely because it was spontaneous. When the whole thing became systematically "done in blocks", negative traits from "stereotyped / mechanistic" to "ridiculous", often showed up.
Some of the LNER Thompson B1s were exotically named after species of antelope, at the suggestion of General Smuts, who christened the first 'Springbok'. Later examples were rather boringly named after LNER directors. 61005 'Bongo' was a bit of an unfortunate name - Gerry Fiennes tells the story of it being rostered one day for the 'Day Continental' to Harwich PQ. A stern reprimand came from 'upstairs' that under no circumstances was this loco to be rostered again for such an important international service.
As I've mentioned upthread -- a class of locos named after those famously speedy and graceful beasts, antelopes, strikes me as a glorious idea; but then I'm a wildlife-lover. Others, plainly, feel and felt otherwise, seeing the names as undignified / grotesque / outlandish -- I've seen adversely-critically cited as such,
Pronghorn,
Puku, and -- as we've seen just above and elsewhere,
Bongo. I see potential trouble nowadays with having a loco named
Bongo, because of sensitivities connected with unenlightened folks' using the figure of speech of the place called "Bongo-Bongo-Land", concerning categories of people who they see as hailing from there and who they would prefer to remain there; for me, it's a splendid name after a splendid animal, "end-of".
If I might dare to venture into the realm of potentially off-colour loco names: there's a thing which I read long ago -- or it's of the sort, re which one wonders whether one only dreamed that one read it. Some seventy years ago, in the very last days of steam development on one of the big US railroads which continued with same, longer than most: the railroad designed and brought into service, a new ultra-modern, extremely powerful heavy-freight steam class. Their publicity department launched a competition throughout the area which the railroad's system served, for a suitably inspiring name for the first member of the class to come into service. A ten-year-old boy's suggestion, attracted considerable notice -- it was
Trojan; as associated with tireless heavy labour, as in the tale of the famous Horse. Unfortunately -- for very many decades back, that name has also been the proprietary name in the USA of, shall we say, an item widely used in the birth-control field: said name, a very widespread colloquial Americanism to refer generically, to said item. One takes it that the class-leader had to end up being named something else. Inevitably, a bit of musing occurs as to whether the ten-year-old competition entrant was an innocent; or precociously dirty-minded...