Alastair Cook made a patient half-century as Essex continued their fine start to the summer by dominating with the bat, eventually ending the day on 335 for three.
Like Cook, Nick Browne and Tom Westley – both of whom have been tipped to play international cricket this summer – were dismissed in the sixties, before Ravi Bopara reached the close 57 not out.
Ben Sanderson took two wickets for Northants, dismissing Browne and Westley, while Richard Gleeson got rid of Cook, who had made 65.
And Sanderson said: “We have been a bit unlucky. We bowled in the right areas and found the edge a couple of times and it’s not gone our way.
“Other days we could have had three or four early and been into them. Hopefully we get a few more tomorrow.
“We were wayward, and when we dropped Cook (on three) that killed us a bit. If that is taken, that is the momentum we needed. If the England captain goes out, they are on the back foot straight away. That was a big moment.
“We were always going to get the most out of it in the morning, but didn’t have much luck. Without that you’re not going to get many wickets.
“They played and missed a lot. We bowled in the right areas. Rory (Kleinveldt) bowled well, was very economical, on another day he’d bowl like that and get five wickets.
“We stuck at it and created a bit of pressure and I think we deserved a couple more.”
Meanwhile, Monty Panesar’s comeback continued as the former England spinner played for Bedfordshire against a Suffolk side containing former Essex seamer Mervyn Westfield.
Panesar took three for 20 from his 10 overs.