Doesn't do much for me personally - too much like chopped-up prose, I mean. I don't know who Tom Flanagan is/was, but that may not matter.
One infers famous Seamus, like all Irish poets, is going on about Ireland again, its language this time. Their gutteral poetry was 'bulled', which sounds like it was forced out by English's frequent use of alliteration. Why one cannot have gutteral alliteration is less clear.
The uvula is at the back of the throad, again a guttural speech reference. The coccyx is the (now missing) tailbone; St Brigid's Cross (http://www.irlonline.com/cross/) is yellowed from being discarded I guess. After having been used to wipe one's backside? Could be, yep. Lots of references to things having outlived their usefulness, right. Now Ireland is bedded down with England, no longer master of its own fate.
And their language is now English. No great loss there, what with Irish showing even stranger spelling and pronunciation than English has. Kidding, sorry! The 'varsity' reference loses me - the root apparently being 'university', but dunno why that matters. The Irish presently use such words as deem or allow instead of suppose, and have absorbed (British) archaic terms into their language.
Macmorris is an Irish gent from Shakespeare's Hank Cinq:
[
www.rhymezone.com]
The what 'ish' my nation note is apparently from that same play:
FLUELLEN: Captain Macmorris, I think, look you, under your
correction, there is not many of your nation--
The pronunciation of 'ish' must be relevant, but again I dunno how.
The last stanza's reference to Bloom is likely not Chesil's buddy Harold, but more the wandering Leopold Bloom in James Joyce's Ulysses.
So, Seamus is lamenting the loss of the Irish tongue and its absorption into present-day English? Likely a correct assessment of the facts, and possibly worth lamenting. Is it well-said, though? Your call - doesn't seem all that clever to me. And its prosey taste puts me off as well:
"Our guttural muse was bulled long ago by the alliterative tradition, her uvula grows vestigial, forgotten like the coccyx or a Brigid's Cross yellowing in some outhouse ..."