But after the interval, Lancashire collapsed, losing four wickets for one run in the space of 24 balls to fall to 115-8, with two each for Gregory and Overton as they ripped through the lower order.
And when Tom Bailey was last man out, caught off a skier at mid-on for 16, Lancashire had been bowled out in just 40 overs.
Lancashire started this match 11 points adrift of safety and having failed to pick up any batting points, genuine survival hopes rested on them performing with the ball.
And they made the perfect start as opener Andy Umeed was caught at second slip off the first ball of the innings as he was caught in two minds over whether to leave Tom Bailey’s delivery.
But Archie Vaughan, son of former England captain Michael, and Tom Lammonby then looked to have steadied the ship as they put on 58 for the second wicket.
However, Vaughan was caught behind off Balderson for 21 and Lammonby (36) edged to first slip off Will Williams in the next over.
When Tom Kohler-Cadmore was also caught behind off Balderson for three, Somerset had lost three wickets for seven runs to slip to 65-4 at tea.