Ryan Moore rode a record ninth winner of this year's Royal Ascot meeting aboard Aloft in the Queen's Vase.
Lester Piggott set the previous post-war best of eight winners in 1965 before repeating the feat a decade a later and Pat Eddery matched that total in 1989.
Aidan O'Brien's three-year-old was the 5-2 favourite for the two-mile contest, despite stepping up a full mile in distance and making his first start since finishing second in the Racing Post Trophy at Doncaster last October.
Moore rode a patient race aboard the market leader before asking for maximum effort from the home turn.
It was hard work over the marathon distance, but Aloft responded admirably considering his lengthy absence and got up to beat Tommy Docc and Future Empire by half a length and the same.
Moore said: "It was a very messy race, I was slowly away and in a bad position and having to pick my way, he was a bit rusty all the way round.
"He's a fair horse this fellow. He's open to all sorts of improvement, it's his first run of the year and you wouldn't know where he could end up.
"I'm very lucky, I get to ride the best horses and that makes a big difference."
Moore added: "It (the record) is not something you think about, we'll think about tomorrow then worry about this."
O'Brien said: "It was his first time over the trip, but he got there lovely.
"He's that (St Leger) type of horse. He stays and likes fast ground and got the trip very well.
"Ryan gave him a great ride and I'm delighted."