Riding Billy Angelo, William took the feature class of the afternoon - the Bunn Leisure Trophy. Drawn exactly half way through the 50-strong class, William jumped an immaculate clear first round then excelled himself in the jump-off phase, producing such a fast and fluent round that he left the following riders no way of bettering his time.
McLain Ward and HH Cannavaro were second, finishing just 0.2sec slower than William, while Ben Maher finished third on Diva II.
William was delighted with the homebred Billy Angelo, who had some time off work recently following injury. "He had bruising on his fetlock and had six months off, so he's only been back for six weeks," said William.
"Last year he lost a bit of form - he just lost his flamboyance and we were scratching our heads a bit as it wasn't obvious and it took a while to find it. Now he feels every bit as good as last year and he's got that flamboyance back."
With a top class field of riders here ahead of the Furusiyya FEI Nations Cup™ tomorrow, William faced plenty of strong opposition - but felt his 11-year-old gelding was more than up for the challenge. "Today it felt very easy for him to be honest, and I think he was as good a horse as there was competing today," added William, who now has the Longines King George V Gold Cup on Sunday in his sights.
The first international class of the show was the Bunn Leisure Vase, which attracted 83 entries. In the end it was a French one-two, with Julien Epaillard and Sheriff de La Nutria LM winning ahead of compatriot Nicolas Delmotte and Parlameme.
"I think in future he will be a Grand Prix horse, he just needs some more experience," said Julien, who called the ground conditions at the All England Jumping Course 'perfect'.
In the showing classes, it was all about the hunters - with Allister Hood and Zoe Turner's Hoppy Jumping taking the Les & Nadia Edgar Supreme Hunter Championship. In reserve were Jayne Ross and Time 2 Reflect.
Tomorrow, eight of the leading showjumping nations in the world will be competing as teams of four in the Furusiyya FEI Nations Cup™, which gets under way at 2.15pm.