Catherine smashed the record by almost 10 sheep an hour, hauling 28 tonnes of sheep on to the board, and clipping more than 1.6 tonnes of wool off them across the day.
Sir David was unable to be present but, watching it live-streamed mid-afternoon, said he was particularly proud of the quality she achieved.
“It showed the benefits of a winning competition career,” he said.
Catherine is one of New Zealand’s most successful female competition shearers.
She had a quality rating of 10.4, well within the threshold set by the World Sheep Shearing Records Society, and considered by most onlookers as “amazing” considering the struggle with “stroppy” sheep during the day.
Sir David said Catherine and new lambshearing record-holders Megan Whitehead (686 lambs in eight hours) and Sacha Bond (720 lambs in nine hours) had taken women’s shearing to a new level.
“I look forward to seeing them in women’s events and other competitions throughout the grades later in the season.”
On hand to see the effort was Wairarapa shearer Amy Silcock who had held the record for just three days after shearing 386 near Pahiatua on Sunday.
Starting at 7am, Catherine Mullooly sheared successive two-hour, above-record-pace runs of 116, 117 and 116 before passing the target about 3.40pm on Wednesday afternoon and the magic number 400 soon afterwards, with still over an hour to go to the finish at 5pm.
Signing off with 116 in the last run, after one was rejected by the four-man Records Society referees panel, she averaged over 58 sheep an hour throughout the day.
Her effort also surpassed the women’s nine-hour record of 452 in the last quarter-hour.
Referees panel convenor Andy Rankin, of Loch Lomond, Scotland, saw her shear in Scotland some years ago and said she was a good Senior shearer he knew would succeed at the top “if she kept at it”.
“It was a good record,” he said, adding the good quality of the shear, and the organisation of the day, made it easier for the officials.
Catherine has won competitions in the Junior, Intermediate and Senior grades and was a quarterfinalist in the New Zealand Merino Shears Open championship in Alexandra in September.
She had a big team of supporters, including timekeepers and now fellow record-breakers Coel L’Huillier and Daniel Langlands. Another record-holder Kaleb Foote monitored the gear.
She was also being cheered along by her father Myles Mullooly and his partner Audrey Tamanui-Nunn, and her own partner Ardy Donnelly and sons Brynn, 3, and Coel, 1.
A team of woolhandlers and others helped with her physical wellbeing during the day.
The shearing sports focus now turns to the resumption of the competition season at Duvauchelle, Banks Peninsula, tomorrow, and a five-stand lamb shearing record in Southland on Sunday.