The pair scored 78.04% in the grand prix special — beating their previous record of 75.25% from ’s-Hertogenbosch CDI (NED) earlier this year.
Only German Olympic gold medallist Isabell Werth (Satchmo) beat Mistral Hojris in the grand prix and special.
Laura said: “Before the flying-changes he was absolutely flying on 82%. We had a small mistake in our changes as he got a little distracted, but it’s a close arena and overall I was delighted with him. He was relaxed, but totally on my aids — a dream to ride.”
Laura also won the grand prix for kür riding her father Wilfried’s Andretti H with a personal best of 71.31% . They were second in the kür with 74.20%.
“Andy went the best he’s ever gone in the grand prix,” said Laura. “He was thrilled with himself showing off his first placed rug to Alf [Mistral Hojris].”
Compatriot Fiona Bigwood was second to Laura in the grand prix for kür on her 10-year-old chestnut gelding Wie Atlantico, scoring 68.51%. Fiona and the former Spanish international team horse were also third in the kür with 73.45%.
International teams director Nick Burton said: “These are really exciting scores. Fiona and Wie Atlantico are growing in confidence every time out and producing pleasing results, while Laura’s fantastic achievements make her a very serious medal contender at future championships.”
Both riders are in contention for a place on the European team to be announced on 14 August.