This added to Leslie's preparations for the Rio 2016 Paralympic Games.
He will now be the favourite to take home the gold medal, which is testament to his number one ranking in the medley.
The record-breaking swim was not a planned part of Leslie's build-up to Rio but he does feel like he is in good stead going forward. "Breaking the world record wasn't a goal as such, the goal was more about executing a race plan in a pressure situation and working on control," he said.
"I'd say I'm building well, things are coming to fruition at least. I feel the cross training I've been doing with wheelchair rugby also is starting to pay dividends. It's not long now."
With less than three months to go before Rio, the next stage of Leslie's preparations is very straight-forward.
"Next up is simple, lots of training. We're about to go into a speed phase so there will be lots of fast swimming and working on being fast but controlled."