Dickson, who was born in South Africa but holds a UK passport, has scored 824 runs at 54.93 in this season's County Championship, with four centuries. He signed for Durham, initially on loan, from Kent in 2020 but recently informed the club that he wanted to return south for family reasons.

"Sean has been an outstanding member on and off the field since joining the club two years ago," Durham's director of cricket, Marcus North, said. "Unfortunately for Durham, Sean has requested to leave so he can relocate to the south of England to be with his fiancé, his daughter Remi and family.

"We thank him for his contribution and wish him success in the future at Somerset."

Dickson averaged 38.46 for Durham in first-class cricket, and 37.36 in List A as part of the side that reached the final of the 2021 Royal London Cup. His highest first-class score remains the 318 he made for Kent in 2017.

Somerset's director of cricket, Andy Hurry, said: "To secure a player of Sean's quality is a coup for the club. He is a proven performer with the bat at this level and has strong aspirations to play on the very highest stage.

"We have been looking to strengthen our batting at the top of the order and Sean fits that bill perfectly. He has started to establish himself as one of the more consistent openers within the English domestic game and will certainly add something to our dressing room.

"Sean is a player that we've been monitoring for a while, and once we were aware of his availability it was paramount that we acted quickly."

Dickson added: "I'm delighted to be joining Somerset. They are a great club with a long tradition and I'm looking forward to getting started. I've admired how they go about playing the game from afar and it's evident when playing against them that there is a genuine buzz about the place. I can't wait to get started.

"It's an exciting challenge and I will be working hard to help the club win trophies. By doing that I will hopefully move myself closer to fulfilling my goals within the game over the next few years."