Somerset 404 (Bartlett 121, Abell 77). middle sex 175 (Simpson 57*, Henry 5-45) and 216 (Stoneman 60, Overton 5-46) by an innings and 13 runs
Overton finished five for 46, aided by fellow sailor Peter Siddle’s three for 57 effort, to send the home side away for a second time, with over four sessions to spare.
Somerset’s victory was only their second red ball success away from Taunton in over two years, the other coming against neighbors Gloucestershire at Bristol last summer.
Stoneman and Stephen Eskinazi, resuming at a consistent 81 for one, drove out most of a grueling first hour, with nearly five overs from Matt Henry and Overton delivering just one leg-bye.
Though Stoneman tucked Overton away for a single soon after to usher in his second half-century of the summer, Middlesex’s solid base was quickly destroyed by a fiery spell cast by Siddle at the Pavilion End.
The sailor’s first delivery was cut for four by Eskinazi, but his second bounced back to clip the Middlesex vice-captain off bail and his departure for 28 marked a well-known mid-range collapse.
Stoneman – bowled the first time by an unplayable Henry ball – was unlucky enough to fall victim to another ball of similar quality from Siddle, which seamed and went into his stump.
Somerset collected three more wickets in the space of 21 balls before lunch, with Overton responsible for Max Holden and John Simpson to roll up the first delivery of Jack Leach’s spell that previously pinned Robbie White’s leg.
Luke Hollman and Ryan Higgins showed some fighting spirit after the break, with the south-hander driving Henry twice from the back foot to the short boundary as he contributed 28 to their seventh wicket partnership of 44.
Although Hollman was caught at third slip, Toby Roland-Jones took over by giving Leach the attack and also hit Overton over long-on for two fours in a cameo of 27 off 24 balls.
But Overton had the final say bowling the Middlesex skipper before completing his side’s win as Higgins (31) hooked him from long range into the safe hands of Lewis Gregory.