According to the Return of Mares, which has been published by Weatherbys, 84 different stallions in Britain and Ireland covered a three-figure book of mares in 2026, a simple but effective means of deducing which sires are currently en vogue when it comes to the unforgiving business of standing stallions.In total, the number of stallions standing in Britain and Ireland during the latest breeding season was 223, down from 230 in 2025 and 269 in 2024. That means that over 37% (84/223) of all stallions covered at least 100 mares and, between them, the busiest 84 were responsible for 13,769 of the 17,738 total recorded coverings, which equates to around 78%.Whether that is a healthy situation, the narrowing of the gene pool that comes with such large numbers of mares being sent to a select group of stallions, is perhaps a conversation for another day. Until then, this game that never fails to fascinate will remain a straightforward case of supply and demand, with stallion masters entitled to welcome as many mares through their doors as they consider fit and proper for each individual.Certainly, one stallion with what would appear an insatiable appetite for the job is Tally-Ho Stud's Starman, the busiest sire in Britain and Ireland in 2026, having covered 324 mares at his increased fee of €40,000. That followed the steady stream of success enjoyed by his first crop of two-year-olds in 2025, when the son of Dutch Art joined Frankel and Too Darn Hot as the only freshman sires in the last decade to have come up with four Group-winning juveniles in Europe. They were headed by the G1 Prix Morny heroine Venetian Sun, who again flew the flag for her sire in 2026, notably doubling her top-level tally with victory in the Commonwealth Cup.Of the 84 busiest stallions, 61 of them would have been marketed primarily as Flat sires. They include seven of the top 10, with Starman being joined by the Coolmore quartet of Delacroix (282), Camille Pissarro (278), Henri Matisse (248) and Sioux Nation (246), another Tally-Ho resident in Mehmas (245) and Yeomanstown Stud's Sands Of Mali (244), who covered by some way his biggest book of mares in his first season at the County Kildare farm, following five seasons at Ballyhane Stud.Mehmas and Sioux Nation regularly feature among the busiest Flat stallions in Europe, the latter having topped the table in 2022, 2023 and 2025. He can perhaps expect another surge in popularity next season, with the three-time Group 1 winner Sun Goddess featuring among his star performers on the track in 2026.Delacroix, Camille Pissarro and Henri Matisse led the way among the Flat stallions embarking on their first seasons at stud in 2026, with three-figure books also coming the way of Maranoa Charlie (233) at Tally-Ho; Capital Stud's Topgear (197); Lead Artist (173) at Juddmonte's Banstead Manor; Elite Status (150) at Whitsbury Manor; Darley's Dalham Hall resident Rosallion (145); Arizona Blaze (137) at the Irish National Stud; National Stud newcomer Diego Velazquez (126); Inisherin (111), also at Dalham Hall; and Rathbarry Stud recruit Unquestionable (100).The busiest newcomer to the National Hunt ranks was the Irish Derby hero Los Angeles, who covered 273 mares at Castlehyde Stud in his debut season on the Coolmore NH roster. Only stud-mate, Maxios (287), the sire of this year's Cheltenham Gold Cup winner Gaelic Warrior, was busier among the National Hunt brigade, with Crystal Ocean (265) also occupying a place in the top 10 and Poet's Word (239) only narrowly missing out.It was also heartening to see that Walk In The Park, who in April was crowned champion National Hunt sire in Britain and Ireland for the third consecutive season, covered 152 mares at the grand old age of 24.Back in 2005, Walk In The Park produced his best effort on the racecourse when chasing home the much-missed Motivator in the Derby at Epsom, with a certain Dubawi passing the post another three lengths behind him in third. Thankfully, Dubawi is also still going strong, albeit the former champion sire is now covering much smaller books than in his prime. A total of 60 mares reportedly came his way in 2026, including illustrious names such as Bluestocking – who sadly slipped her foal – Mawj and Nashwa.Frankel, who commanded a fee of £350,000 at Banstead Manor in 2026, seeing him tied with Dubawi as the joint most expensive stallion standing in Europe, welcomed a typically elite book of mares numbering 202, including Group 1 winners and producers such as Lillie Langtry, Mecca's Angel and Quiet Reflection, to name just a few.Having previously claimed the title in 2021 and 2023, Frankel will this year have to settle for the runner-up spot in the British and Irish sires' championship, with Night Of Thunder all but guaranteed to make it back-to-back triumphs after Ombudsman ran away with last weekend's G1 Champion Stakes at Ascot.Night Of Thunder covered 180 mares when standing for a fee of €200,000 at Darley's Kildangan Stud in 2026, including the dams of his top-level winners Desert Flower, Dynamic Pricing, Estrange and Gewan, not to mention Syndicate, the dam of the aforementioned Ombudsman, now a five-time Group 1 winner after his Ascot exploits.Of the stallions currently occupying a top 10 position in the sires' championship, Kingman was the busiest with 206 mares visiting him at Banstead Manor, ahead of Camelot (198), Blue Point (179), Starspangledbanner (158), New Bay (150), Sea The Stars (146), Lope De Vega (138) and Dark Angel (103).That breeders had the confidence to send 158 mares to Starspangledbanner after his well documented fertility problems at the start of his career is testament to the work of those closest to him – not to mention his burgeoning reputation as an elite stallion – while another interesting case study is Havana Grey, who covered 147 mares during the latest season. That's no small feat – pardon the pun – for a stallion whose opportunities are limited because of the height restriction imposed by Whitsbury Manor, with only mares measuring 16hh or smaller being accepted.Havana Grey and Starspangledbanner are two examples of stallions who have taken far from conventional routes to the top, with Havana Grey standing for a fee of just £6,000 at one stage and Starspangledbanner barely managing to get 30 foals on the ground in his early years at stud.Looking at the Return of Mares for 2026, a few sires deserve a mention for reviving their own fortunes following a lull of sorts the previous year. Saxon Warrior, for example, was sent 114 mares at Coolmore during the latest season, up from 44 in 2025, while Phoenix Of Spain went from 68 to 122 at the Irish National Stud.A change of scenery seemed to do the trick for King Of Change, who covered 111 mares in his debut season at Tweenhills, up from 38 in 2025, while the book of mares received by Cracksman doubled from 40 to 80 during his first season in a dual-purpose role at Yorton Stud.Bayside Boy, meanwhile, has been one of the standout first-season sires in 2026, with 16 individual winners – including a pair of black-type winners – emerging from his 36 first-crop runners in Europe. Clearly, the word from trainers in the first half of the year was already positive enough to encourage breeders to support him in a big way, with 158 mares visiting him in 2026 after he covered only 65 the previous year.The 20 busiest Flat stallions in Britain and Ireland in 2026Starman, Tally-Ho, 324Delacroix, Coolmore, 282Camille Pissarro, Coolmore, 278Henri Matisse, Coolmore, 248Sioux Nation, Coolmore, 246Mehmas, Tally-Ho, 245Sands Of Mali, Yeomanstown, 244Maranoa Charlie, Tally-Ho, 233City Of Troy, Coolmore, 213Kingman, Juddmonte, 206Frankel, Juddmonte, 202Camelot, Coolmore, 198Topgear, Capital Stud, 197Ghaiyyath, Darley, 190Chaldean, Juddmonte, 181Night Of Thunder, Darley, 180Blue Point, Darley, 179Baaeed, Shadwell, 178Big Evs, Tally-Ho, 173Lead Artist, Juddmonte, 173The post Return of Mares: Most In Demand, Most Expensive and Most Improved appeared first on TDN | Thoroughbred Daily News | Horse Racing News, Results and Video | Thoroughbred Breeding and Auctions.