Although there is some crossover between the two Sections (and to a certain extent with the Section C Cobs), the two do have distinct sire lines. The following is an overview of the successful sire lines from the Welsh Mountain Ponies (Section A) and the Welsh Ponies (Section B).
Welsh Mountain Ponies
Without a doubt, the pony that forever changed the Mountain Pony was Dyoll Starlight. Starlight, foaled in 1894, founded a dynasty that would cause the breed to become known as the "most beautiful ponies in the world". Starlight was bred and owned most of his life by Welshman Meuric Lloyd, until Lloyd's failing health would eventually cause him to sell the aged Starlight to Lady Wentworth (of Crabbet Arabian fame). Sadly, misunderstanding developed between the Lloyd family and Wentworth, and conflicting reports arose surrounding Starlight's origins, with Wentworth claiming he was part-Arabian and the Lloyd family insisting that he was of pure Mountain breeding. (The registry records him as pure Mountain Pony, and documents do seem to most strongly support this). Despite the controversy he would go on to sire such greats as Bleddfa Shooting Star (sire of Grove Sprightly and double-grandsire of Tregoyd Stalgiht), Grove King Cole, and Greylight (who would later be exported to Australia and have a profound impact on both Welsh Ponies there and the Australian Pony). His influence would be even stronger through his female descendants.
In 1935, the breed acquired another great sire in the form of Coed Coch Glyndwr. Although descended from Starlight twice through his dam, he was from a completely unrelated sire line (the hackney Prince of Cardiff). This sire line would also produce the mare Coed Coch Serliw. Of the Royal Welsh show Campions from the years 1947-1972, over half (34 of 50) would trace back to Glyndwr, Serliw or both. His best known sons would be Coed Coch Serddwr (sire of Coed Coch Madog), Clan Dana (particularily influential in the United States), Clan Tony (sire of Clan Pip) and Shalbourne Pendragon. Glyndwr was responsible for adding futher refinement and beauty to the breed.
Originally Section B was established for the crofter's work pony, which were essentially poinies of the cob type (ie, capable of carrying a grown man). In the 1930s, demand for children's riding ponies neccessitated a change, so Section B was set aside for riding ponies while Section C was established for ponies of cob type.
In the beginning, lighter-built poniies of at least 50% Mountain Pony blood were accepted into the registry. The most influental of these early ponies were Craven Cyrus (half-Arabian) and Tanybwich Berwyn (half-Barb). Another prominent stallion was the blue roan Criban Victor, who was a Welsh Mountain-Welsh Cob cross. Many American Section Bs trace to Criban Victor through his sons Coed Coch Blaen Lleuad and Coed Coch Ballog.
Because there were so few Section B stallions, two stallion from FS1 mares were allowed to "jump" a generation and be registered. These two stallions were Coed Coch Pawl and Reeves Golden Lustre (who had already proven to be a successful sire of British Riding Ponies). But the big turnaround in Section B Ponies would come with the birth of four stallion all in the same year. These stallion (all out of FS2 mares) were Solway master Bronze, Brockwell Cobweb, Downland Dauphin, and Chirk Crogan. To give an idea of just how depleted the numbers of Section B Ponies were at the time, there were only 26 registered Welsh Ponies (B) in 1959.
Of these four stallions, the first was Solway master Bronze. He was by Coed Coch Glyndwr and out of Criban Biddy Bronze (who traces back to the dam of Criban Victor). Like Golden Lustre, he produced many prize-winning British Riding Ponies in addtion to registered Welsh ponies.
After that there is Brockwell Cobweb, whose influence in the United States is mainly through his grey son Brockwell Spider. Cobweb was a dark chestnut rabicano with a blaze and hind socks and was primarily Coed Coch and Wentworth breeding.
Downland Dauphin has had a great deal of influence on the modern Section Bs, particularly through his son Downland Chevalier. ALthough Chevalier grew over height and therefore was never shown, his contribution will probably cause Dauphin's to be the prominant sire line of the future. Another Downland pony influential in this country is Downland Drummer Boy, maternal half-brother to Dauphin.
The last pony, Chirk Crogan (along with his full brother Caradoc) were sired by Blaen Lleuad. lleuad was later exported to the United States, and his grandson Wickenden Osprey is a popular sire here.