Dan Lawrence will leave his home club Essex at the end of the season after agreeing a shock move to Surrey on a three-year contract.
Lawrence, the spare batter in England's Ashes squad, grew up in Chingford and has played for Essex's first team since the age of 17, having previously represented the county's age-group teams.
Essex said in a statement that they had offered him a "very strong three-year contract" earlier this summer, but he declined a renewal and has agreed terms with Surrey. He will remain available for Essex for the rest of the season, around his England commitments.
Lawrence said that he was leaving the club "with a heavy heart" and that it had been "an incredibly difficult decision" but believes that moving to Surrey, the defending county champions, would help him achieve his ambitions to become an England regular across formats.
"It is with a heavy heart that I will be leaving Essex CCC at the end of this season," he said. "Essex is the county who taught me how to play the game, developed me as a person and allowed me to play the sport I love professionally.
"At this stage of my career, I believe a move to The Oval offers a new challenge and would hugely benefit my own ambitions. Whilst an incredibly difficult decision, it is one that I am taking to continue my development as a cricketer."
Lawrence's Essex contract expires at the end of the summer and Surrey have moved quickly to secure his services. Counties are only allowed to approach out-of-contract players from June 1, and Alec Stewart, Surrey's director of cricket, said he was "exceptionally keen" to sign him when the opportunity arose.
"I first saw Dan play as a 17-year-old when he scored 161 against us in just his second first-class game, and it was obvious he had the potential to become a very special player," Stewart said.
"After just a couple of conversations it was apparent he wants to fulfil his ambitions of being the very best player he can be and become an England regular in all formats. He felt making this tough cricket decision and moving to The Kia Oval would help and we will do all we can to support his aims."
Anthony McGrath, Essex's head coach, said that Lawrence would still be considered for selection for the rest of the season, despite the club's disappointment about his departure. "Dan has expressed his desire to move to Surrey which we accept after turning down our contract offer," he said.
"He has been an important part of our achievements in recent years, and we are all proud of his progression to the international stage, which includes the opportunity to play in the Ashes this summer. He is an exemplar of the success that Essex's academy has had in producing homegrown cricketers who go on to represent their club and country.
"Dan still has a role to play in the remainder of the season as we strive for silverware across all formats. He is dedicated to working towards our aims this season as a club and will still be available for selection around his other commitments."
His move will add further international quality to Surrey's Championship batting line-up, which already contains a number of recent England caps in Dom Sibley, Rory Burns, Ollie Pope and Ben Foakes, as well as England Lions' Jamie Smith.