Cambridge, we learn, is not quite as posh as we thought. The University, that is, not the town. The town is more or less the standard mix of the Bash Street
Kids up one end and Walter's softies down the other. But the University has long been a finishing school for Lord Snooty and his fellow assorted toffs
No longer, though. The university now takes over 60% of its undergraduates from non-public schools. This places it well down the list of public-school-heavy educational establishments, behind Oxford (needless to say), Durham and Bristol, among others.
Since public (i.e. private) schools currently educate an estimated 7% of our youth, and 14% of our sixth-formers, this does not represent a crisis for privilege, exactly (and anyway, there’s always the Royal College of Music or the Royal Agricultural College if all else fails). But it does mean that we’ll be hearing fewer triphthongs when we’re out and about.
A debate rages on the Internet as to whether English is a language of triphthongs or only of diphthongs. A diphthong, as my students are only too well aware, is an elision of two vowel sounds; unlike a pure vowel sound, diphthongs require a considerable movement of the tongue and other mouth parts to produce. Thus the vowel sound in high is really a movement from /a/ to /i/, or the sound in toy is a movement from /o/ to /i/, and so on.
A triphthong (if it exists) is a more acrobatic version of the diphthong, a three-way movement of tongue and jaw and lips and the rest. But does it in fact exist in English? Some will tell you that the vowel cluster in words like power or idea or fewer are essentially triphthongs; others (probably Americans) will classify the words as merely polysyllabic.
But it all depends what you mean by English. There is a version of English, now sadly somewhat endangered, favoured by the cream of public-school-educated twittery, which will essentially lose the intrusive /w/ sound in power (although, is it intrusive if it is written into the word?) and string out the vowels like the lingering drift of a fine wine. Pronounced thus, flower power would amalgamate into two extraordinarily long and clotted syllables.
We should be able to look to poetry for some help here. What poets make rhyme, or scan, tells us a lot about how they might have expected to pronounce them. Thus Keats's 'but on the viewless wings of Poesy' must separate out the vowel sounds in Poesy if it is to respect the metrical scheme of 'Ode to a Nightingale'. Keats was, by Lord Byron's account, a bit of a barrow boy, so that makes sense. On the other hand, he was also a Romantic Poet (i.e. a bit of a weed), thus flower in 'I cannot see what flowers are at my feet' must be triphthongised, to some extent, if you are going to squeeze it into the line.
The jury is out, then. Not that anyone is judging you on how you speak, of course.