In Ghost in the Machine, one of the TV Inspector Morse series, Morse deduces a suicide note to be a forgery because of a spelling convention: an educated person, he declares, would use spellings such as "realize" (rather than "realise").
I don't suppose I'm the only viewer to have boggled at this. Morse is actually expressing a local prejudice; like his creator Colin Dexter, Morse has Oxford University connections. The Oxford English Dictionary uses "-ize" endings on a number of words whose etymology tracks back to Greek "-izein" and Latin "-izare" (canonize, characterize, organize, idolize, patronize, realize, etc). It lists "-ise" merely as "a frequent spelling of -ize, suffix forming vbs". Oxford University Press, Cambridge University Press, Nature and (due to Noah Webster's choice on the same grounds) Americans go with this convention. It is, however, a minority one in the UK, where most publishers and mass media printers go with "-ise" endings; even The Times, a long-standing "-ize" user, dropped the convention in the 1980s. However, both "-ize" and "-ise" still coexist; the choice comes down to etymology vs custom-and-usage.
Locally, we have a very similar issue: is "Topsham" pronounced "Top-shəm" or "Top-səm"? (This symbol - ə - is a schwa). It's a matter of observation that the majority pronunciation is the former; yet magazine articles regularly state that the latter is definitively correct because of the town's origin as "Toppa's Ham" (possibly a self-perpetuating factoid because it's the one favoured by the subset of people that journalists consult on such matters). In the distant past, the etymology and pronunciation matched - historical documents are full of references to Topsam, Topsom and even Apsam - but now the spelling is standardised to Topsham, this connection has loosened and usage strongly favours "-shəm". Nevertheless, it's a common assertion that etymology trumps usage. Even in 1943, a Devonshire Association Report and Transactions here stated that "Topsham was habitually, if incorrectly, pronounced Top-sham, or rather Top-shum" - a classically prescriptivist statement (the descriptivist view is that the habitual pronunciation is by definition the correct one).
The background to the Top-shəm/Top-səm divide is complicated, with elements of social class and affiliations and, as Peter Howard's Heritage: Management, Interpretation, Identity says, "insider" versus "outsider" pronunciations. Characteristically, "insider" pronunciations are the historically long-standing ones that tend to disappear as a community becomes less isolated, but in the transition period they tend to be embraced by "elite incomers"as a shibboleth. Ultimately the Top-shəm/Top-səm situation is very similar to the "-ise" vs. "-ize" one. Neither version is correct or incorrect; it merely depends whether you buy into etymology or usage as defining pronunciation.
This is actually quite a common situation with places originating as "Someone's Ham". Generally there's a historical drift toward "-shəm" pronunciation with increasing urbanisation as "outsiders" outnumber "insiders". Nowadays a number of fairly isolated places retain the "-həm" ending: Masham is pronounced "Massam", and Bosham - a Sussex village remarkably similar to Topsham - is "Bozzum". Others, such as Lewisham, Amersham and Evesham, are invariably pronounced "-shəm". Lewisham moved from "Loosam" centuries ago, and Cosham has moved from "Cossam" to "Coshum" within the 20th century. Topsham, it seems, has just gone over the same cusp, and is ultimately likely to follow the trend.
Liverpool Mercury, September 11, 1835, concerning a speech made by Lord Brougham, when he raised laughs by speaking of "Lunnon" and "Brummagem". A correspondent from Wigan pointed out that these were acceptable, notes the tension even then between provincial and metropolitan pronunciations, and gives a list of other pronunciations listed as correct in the 1759 book Every Young Man's Companion. More are quoted at the weblog Turpin.
How reliable the guide is for the period, I don't know. The author, William Gordon, was Scottish, and this might have affected his taste on pronunciation (e.g. he might have preferred "Lunnon", still-extant in Cockney/Estuary English, because it matches the Scots Lunnon). Conversely, being an 'outsider' might make him more reliable - non-natives can often bring an unbiased ear to commentary on language (I'm thinking of Otto Jespersen, and of Steve Thorne's work on non-native perception of Brummie). Whatever - it's interesting 250 years later to see which are still perfectly normal and which, though they make sense in regional accent, have long gone obsolete. (Click on the graphic to enlarge).