"It was thanks to the late Billy Cotter that we found the horse in the first place," Marily remembers.
"He was eight at the time and had done a few seasons in Cork and covered a handful of mares. He actually came to us unbroken but Susie had him riding in a few days and had him show jumping in no time."
Within a short few months the stallion had shown so much potential as a sire of performance stock the decision was made to move him to Ashfield and set up Suma Stud in the spring of 1978.
By then Susie had retired from the saddle and the pair soon found themselves running a busy breeding yard.
One of the first mares to produce a foal by him while standing at Suma was Enniskeane Countess.
In the preceding years she had bred a colt by the sire, later named Enniskeane Pride, and her fourth colt went on to be another successful UK-based stallion, Enniskeane Prince. One of her most prolific daughters was Kildalton Countess, by Ben Purple and dam of six stallion sons - Glidawn Diamond, Diamond Lad, Diamonds are Trumps, Kildalton King, Kildalton Gold and Pride of Kildalton.
"Pride of Shaunlara changed our lives," Marily and Susie admitted.
"If we had not found him, we would never have been so involved with Irish Draughts, or developed our stud the way it has."
Throughout his career at stud he went on to sire numerous other stallions, most notably Prospect Pride, Pride of Toames and King Elvis, in addition to a host of top broodmares including Tara Sky.
Sold to Fintan Branigan as a yearling, Tara Sky later produced the hugely popular performance sire, former RDS champion Crosstown Dancer, as well as the show jumper Suma's Sky's Ablaze (by Horos).
"At time we were doing our best to revive the athletic Irish Draught and we were delighted when he also sired our first ever pure-bred ID filly Rathdrinagh. Later named Coral Sea, she was jumped at international level, as was her full-brother Suma's Oscar."
Just as the progeny of Pride of Shaunlara were beginning to make waves, Marily and Susie spotted another sire, Blue Peter, who they believed would strengthen the breed even further.
"We had seen some lovely mares by him and he had fantastic movement so we were lucky to get him, even though he was 20 at the time."
Among his offspring were the sires Blue Henry and Blue Rajah, while his daughters included Blue Hills, Mrs Thatcher and Whippy, the result of a crossing with Tara Sky's dam Softee.
While Mrs Thatcher came to Suma as a two-year-old and was dam of such performers as The Iron Lady and champion show mare Thatcherite, Whippy started and ended her life at the stud, but not before she left her legacy in 15 foals, most notably Huntingfield Rebel.
His grandsire Glenside had followed Blue Peter in joining the Suma roster having been sourced in Galway, and his first produce was the hugely successful stallion Glenagyle Rebel.
Glenagyle Rebel's dam Brosna Queen (by Rusheen Hero) had been sourced from the well-known author Marjorie Quarton, and the cross resulted in the 'dream colt' who jumped to Grade A and passed on his genes to such top show jumpers as James Kernan's Special K before being exported to Zimbabwe.
While it was a difficult decision at the time to let him go, horses were their business, having also sold Huntingfield Rebel as a foal through Tattersalls, but only to buy him back as a seven-year-old and send him jumping with Dermott Lennon.
In the years that followed Huntingfield Rebel sired multiple winners both in performance and in the show ring, including the broodmare Suma's Blueprint, sold for a record €18,000 at Cavan in 2005, and such popular sires as Rebel Mountain, Rosheen Yeats and Oh Carol's Rebel. He died last year at the age of 24.
The year 2004 was a turning point in the future of Suma Stud as it was when the property in Meath was put on the market and Marily and Susie were forced to re-locate to Graignamanagh, and ultimately downsize as retirement beckoned.
"As part of the dispersal we'd held an auction of our youngstock through Tattersalls and among those was Suma's Zorro, who topped the figures when sold to Joanne Sloan-Allen for €7,700. That mare is now jumping internationally for Egypt." By Ard VDL Douglas, her dam Vixen's Frolic had come from the same family as Marily's top show jumper Fox's Frolic.
In the preceding years Marily and Susie had been instrumental in bringing Ard VDL Douglas to Ireland, while they are also credited in kick-starting VDL Arkansas' jumping career here with Clem McMahon in addition to him siring a host of top performers over the years.
"I suppose we were one of the first to get into warmbloods at the time," Marily remembers, but now things have changed and we just have a few broodmares at home being covered by foreign stallions.
In saying that, the legacy of Suma Stud is set to continue for another while yet with descendents of Suma's Legacy and Vixen's Frolic now gracing the fields of Suma Stud on the edge of the River Barrow.
"It's the most beautiful place here and we wouldn't want to live anywhere else now," Marily and Susie concluded.