Jack Leach will return home from England's tour of South Africa following the left-arm spinner's struggles with illness.
Pakistan batsman Babar Azam will return to Somerset this summer for a spell in the T20 Blast and County Championship.
Somerset are set to sign experienced South Africa seamer Vernon Philander on a Kolpak deal.
Somerset sign Australia Test batsman Matthew Wade as an overseas player for the first half of the 2020 County Championship season.
Audio & Video
Marcus Trescothick's parents, Lin and Martyn, reflect on their son's incredible career for Somerset and England as he retires.
Jack Leach, who came within eight runs of a maiden Test century against Ireland, talks DJ-ing at Jos Buttler's wedding, supermarket work and living with Crohn's.
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