Yorkshire’s Alex Lees underlined his status as a star in the making with a record-breaking 275no to help put his team in a dominant position against Derbyshire at the halfway point of their LV= County Championship match at Chesterfield today.

Lees spoke of his delight at becoming the county’s youngest ever double centurion at the age of 20 years and 95 days, while remembering his father Simon, who died of cancer in May 2011.

The left-handed opener’s achievements were then put into perspective as Derbyshire slipped to 83-5  in reply to the visitors’ mammoth 617-5 declared, the ninth highest total in their first-class history. They closed on 94-5 from 39 overs.

“I've worked hard over the years, and my late father would be rather happy. Times like this are really rewarding and extra special,” said the Halifax-born player, who beat Richard Blakey’s previous record from 1987 by 130 days.

He had shared a 311-run stand for the second wicket with Phil Jaques during yesterday’s opening day, the county’s highest partnership for that wicket in first-class cricket against Derbyshire.

But today he posted the third highest individual score on this ground, the equal 11th highest in Yorkshire’s history and the highest since Darren Lehmann’s 339 against Durham at Headingley in 2006.

It has obviously been a difficult couple of years for Lees, who was earmarked as one to watch by White Rose president Geoffrey Boycott in January.

“If you saw him at Lord’s (where he scored his first hundred last month) and here, he looked up and acknowledged his dad,” said Yorkshire’s director of cricket development Ian Dews, who has known Lees for years.

“I missed the hundred at Lord’s, so I mentioned it to him when he came off. He said ‘I know he’s watching’.”

After sharing century stands for the third and fourth wickets with Andrew Gale and Gary Ballance, Lees was also delighted to pass Martyn Moxon’s career best 274 during his 436-ball innings.

He then watched Steve Patterson and Jack Brooks strike twice after tea to leave Derbyshire in tatters.