Well, you've really got to split today's NH into two parts - hurdling, and chasing, redhead. Today, yes, as I've said on here and elsewhere for years, hurdling has been the next step for many ex-Flatties. Not a Flat Seller goes by where the auctioneer doesn't trundle out the now well-worn chestnut, "Nice big 'orse. Plenty of scope to him - bound to make up into a decent hurdler." I've bet sweets on it with our manager at Brighton! I've also been rather excoriating and called hurdling (in the UK) the dustbin of the Flat and, sadly, to a fair extent, it is. It's full of hastily under-schooled, badly-behaved, unsettled animals hurtling towards an early fall and probably a truncated career. Hurdles haven't been changed, though, because the horses got smaller. They've gone from the hateful flip-back flimsy crap to sturdier types where you either knock them dead flat or flip the foam top off - there's barely any backward flip to them now, which used to catch out back runners and tip them over, causing fatalities. Also, courses like Southwell have adopted the stuffed French hurdle, which is like a mini-chase jump, sturdy, stiff, and definitely not capable of being knocked flat.
As for chasers, you must be aware that many - especially the most powerful - yards are now between 40-60% French-bred. Still plenty of good Irish horses in them, too, but a paucity of British-breds. French-breds are trained from the moment they're backed. They're schooling over fences, small to start with, from the age of two, brought into hurdling at three, and away and over the chases from 4-5. If you watch any French jumps racing (not called National Hunt over there, of course), you'll see that the hurdling is over the stuffed obstacle, the chasing is over a magnificent array of obstacles, all representative of a day's hunting. Where we don't think of the French nation as hunters (which they are), they, not we - shame, shame! - have departed from our hunt-based heritage and now present our runners with two boring, similarly-constructed obstacles: the upright, and the not-very open ditch. The water jump's been reviled and many of our courses grassed theirs over, leaving most of our animals with round after round of the same old stuff.
Again, chase fences were adapted due to high fatalities and, due to the ever-increasing high visibility of these on television from every angle, the need to present spectacles such as the Grand National as more of an extreme test, than an ordeal to be borne. The BHA has recently launched research into why certain fences at certain courses seem to cause more difficulties to horses, and that's why small mods were made at Cheltenham, with good effect this year.
So, in hurdling you may see some imported French-bred hurdlers or horses who've been bred from earlier generations - LINAMIX being a very popular and talented choice. You'll also see loads of ex-Flatties of various shapes, sizes, and abilities.
You'll see in chasing a large proportion of French imports, as you know - KAUTO STAR and his star rivals being fine examples. Big girth, good height, not particularly wide-chested between the front legs, good shoulder. If imported, they're ready-made, ready-to-run, used to tackling a variety of heights, widths, banks, walls, the bullrush (jump right through the reeds), etc., making them very sure-footed. 16.2-17 h.h. is not unusual.
You'll see plenty of stout Irish-breds, too, from good jumps stock. BOB BACK's progeny continue to do him proud. Usually wider-framed than the French, great stayers on the soft. They're used, if they're imports, to the ups and downs of the undulating Irish NH courses, so they're not usually in any trouble at ours. Around the 16-16.2 hh mark. You don't need 'em taller!
British-breds of the olde hunting type of up to the 1950s have declined, yes. That's because speed has become more the essence of British jumps racing and their huge stamina - great girth, short cannons - has been sidelined to the extreme staying races, which are very few, and where the French and Irish have outnumbered them.
There was also a brief flirtation with NZ-breds in the 1990s, all imported geldings, the best of whom was LORD GYLLENE winning the Grand Nasty in 1997. They've been a bit iffy, to be honest - one or two sparklers, the rest no better than average.
What's interesting now is the gradual increase in using some very good German-breds, and the introduction of Eastern-European racers, like Polish-breds. I had the great pleasure of going to the Velka Pardubice a few years ago and seeing the redoubtable mare REGISTANA winning again under the German jockey, Peter Gehm, tragically paralyzed a few months later on Christiaan von der Recke's gallops. She was, like the other Eastern European horses attending, wiry and very strong. Not particularly tall, but immensely agile and athletic. That may well be the way we'll be heading in ten years' time, since everything evolves to meet the changing demands of racing.