But that "someone" would probably be able to identify the composer himself in the vast majority of those cases, otherwise he/she could hardly claim to have a "reasonable degree of familiarity with post-1945 music"... and if the person had such a familiarity with pre-1945 music it's a very open question whether their nationalities could be discerned (I think probably not).

Austro-German, Italian and French ways of doing things were all very different, and had been for many centuries. Discerning the traces of the culture in which one was raised upon a musical personality is not necessarily about nationalism (that is a much more self-conscious phenomenon), more simply an awareness that these things are likely to have an effect, just as they do upon people's accent, some behavioural traits, etc., etc. The same might be said of gender, ethnicity, sexuality, class, etc. - not necessarily all-determining factors, but significant influences. Many do not like to think they might have a 'male' or 'white' outlook on the world, but various women or black people might protest otherwise - certain things seem just 'natural' or 'individual', but like quite different from outside. The same might be said for the traces of the culture in which one grew up and/or inhabits. Who would one cite as a French composer who doesn't remotely sound 'French' in some sense? And if that is difficult, mightn't others hear British composers in a similar manner? I'm very sceptical of British people denying that such a thing exists.

Ferneyhough is a special case, not having lived in Britain for 40 years and developing his adult compositional sensibility (and career) essentially outside. But still his formative years were spent in this country and as a person he does not strike me as 'un-British'. I don't know any German composers, say (to give the most obvious parallel in terms of the musical culture from which he appropriates some stylistic tropes) whose work really sounds like his, even when adopting a similar idiom. A certain degree of detachment from what he is doing (but very different from the type of detachment one finds in Kagel, say - there is an example of a composer who has lived for over 50 years in Germany, but to me does not sound like a German, especially when compared with Schnebel, say), boundaries on the degree of inwardness, may be a factor here.

Well, all discernments of nationality are based upon other knowledge and experience of the culture in question, including its earlier manifestations. If we drew this more widely, I'm quite sure that someone from sub-Saharan Africa would instantly know the difference between European and sub-Saharan African music - both huge categories with tremendous diversity but nonetheless highly distinct.

Sure, I'm just saying that if large-scale distinctions based on region might be clear, then possibly smaller-scale ones might also be. As Westerners, I'm not sure we as individuals transcend time and place at present, notwithstanding possibilities of communication, global travel, etc.

Not quite what I knew as le vice anglaise