The GBR pipeline used to consist of ex-pursuiters (Wiggins, Boardman, Thomas, Armitstead/Deignan) and imports (Sciandri, Froome) with the odd (often Manx) Maverick (Yates, Miller, Cavendish, Kennaugh, Swift) thrown in. That's the GBR blueprint all the way back to the Beryl Burtons and Tom Simpsons of this world, and in a sense, even before the Keen revolution, it worked pretty well for a basically non-cycling nation with no high mountains.
Recently, however, the GBR youth scene seems to have come over all Oranje/Belge, with a steady stream of super quality riders over multiple surfaces - Pidcock, Savkstadt, Ferguson). It's a nice and useful change of pace.
From an Irish perspective it doesn't hurt to be so strong that people like Ben Healy take the Dan Martin route, just as we have an Eddie Dunbar and a Sam Bennett, and a handful of other interesting riders coming through home grown.