Northamptonshire 399 (Crook 88, Willey 76, Copeland 70, Napier 6-93) beat Essex 183 (Napier 73, Crook 4-39) and 207 (Quiney 56, Willey 5-67) by an innings and 9 runs

After missing out on Championship promotion by a point in 2011, Northamptonshire endured a miserable 2012, with only two Championship victories and dire performances in both the CB40 and Twenty20. But a squad that could be backed at 20-1 to be Division Two champions before the season started has so far hinted at possessing the quality, balance and depth to justify talk of Championship promotion.

Under conditions that remained good for batting, David Willey produced a compelling display of left-arm swing bowling to seal an innings victory over Essex halfway through the third day. The highlight was when Ravi Bopara, whose 41 had been a rare source of solace amid the disintegration of Essex's top order, was deceived into playing at a ball that shaped away from him. The dismissal came only a few deliveries after Willey had changed his angle from around to over the wicket, and was his fifth of the innings.

In a match-clinching spell of 6-2-15-3 shortly after lunch, Willey showed an array of talents. He displayed the classic left-armer's trait of being able to shape the ball back in from around the wicket, but it was a ball that went straight on that accounted for James Foster, playing for swing that wasn't there. A spectacular caught-and-bowled then claimed Greg Smith.

It completed Willey's best first-class game yet: match figures of 8-110 to complement a perky 76. As an allrounder and left-armer there may be those saying he could be considered for England, but Willey's bowling, impressive as it was, could do with a little extra pace - and coach David Ripley believes he could yet put on another yard - to trouble batsmen less complicit than Essex's were here. But he would not be undeserving of an England Lions call-up for their match against New Zealand next month.

After bowling out Essex for 183 in the first innings, Northants will have been even more thrilled to have dismissed them for 207 in the second. While the pitch offered some assistance for seamers on the first day, it flattened out - as it often does at Wantage Road - on the second and third. Northants displayed unrelenting discipline, seldom straying from their line outside off stump and trusting that rash shot selection from Essex's batsmen would do the rest.

That it certainly did. Of Essex's top order in the second innings only Bopara and - at a push - Foster could not honestly claim culpability for their dismissals. The wickets of Rob Quiney, who had played well for 56, and Mark Pettini, both swiping outside the off stump attempting to cut balls when more attritional batting was required, were particularly disappointing. They could learn from Maurice Chambers, who played with admirable disciple for his 65-ball 3.

Reflecting on the victory, admitted "it was a good toss to win" and said that the 228 runs added for their last two wickets proved decisive. "They're good players and we said they're good players but they batted - rather than sulking because they're down the bottom - with purpose and that swung the game our way. The match-winning effort was that few hours where the game swung massively in our favour."

Ripley believes Northants could win Championship promotion. "Absolutely. I've said right from the start we've been very competitive generally over the years in four-day cricket. We perhaps haven't been the same in one-day cricket and we've focused hard on our one-day skills."

"We've got a good balance in that seam attack. Trent Copeland is relentless and has got good skills; Andrew Hall is a master of hitting the seam; David gives us left-arm and swing; and Steven Crook gives us a bit of cutting edge and a bit of pace so I think we've got a good variety in that attack."

On Willey, Ripley added: "He's come a long way in 18 months. He's a good professional, he looks after himself very well off the field. He's an absolute athlete - his caught-and-bowled, not many in the country would have taken a catch like that."

Based on this evidence, there is every chance a disciplined side with the longest batting line-up in the country - and, in Matthew Spriegel and Olly Stone, some solid players who have yet to appear - may yet challenge for promotion. For Essex, this performance, coming on the back of conceding 409 for 5 against Gloucestershire at Chelmsford last week, will raise some serious questions. Their coach Paul Grayson was unavailable for comment.

Instead, it was left to Bopara. "They bowled relentlessly on a length, they bowled very well as a unit which we can learn from I think," he said. "It really showed us how to get stuck in with the ball. I didn't think anything was special when it came to their batting - we had them 170 for 8 but unfortunately their last few batters played really, really well and you've got to give it to them." He admitted that "we kind of did lose control" during Northants' game changing lower-order intervention.

Compounding their problems, Essex could yet face a points penalty on account of their slow over-rate in this match.