Mitchell and Blundell have been constant irritants to England over the course of the series, sharing big stands of 195 and 236 at Lord’s and Trent Bridge, and the pair once again combined to shut down the home attack.
A sequence of four wickets in a rousing evening session on day three had put England firmly in control of the match, but they drew a blank over the course of two difficult hours on Sunday.
The Kiwis added 86 runs without loss, stretching their lead to 223 at lunch, with Mitchell continuing to ride a run of career-best form.
He was 44 not out in a score of 264 for five, turning in another impressive showing on the back of three centuries in the series to date, and in the process became the first touring player to score over 500 runs in a Test series of three matches or fewer in England.
Blundell, who has also proven himself a player of skill and determination at number seven, was 45no at the break.
England’s seam attack were unable to generate any real menace, with the ball soft and unresponsive and the pitch playing sedately, but spinner Jack Leach came close to a crucial breakthrough when he straightened one into Mitchell’s front pad on 17.
Umpire Marais Erasmus raised his finger to confirm the lbw decision, but the verdict was overturned by DRS, with ball-tracking showing the ball clearing the top of the stumps by a distance. For England, that was as close as they came to a much-needed breakthrough.
They took the second new ball just before lunch, with Stuart Broad and Matthew Potts finding a little extra zip with the fresh Dukes in hand as they managed an over each.
Whether they can use to cause real damage at the start of the afternoon’s play is likely to be critical to England’s hopes of keeping their eventual chase in sight.
England had started the day with an unexpected personnel change, after wicketkeeper Ben Foakes tested positive for Covid-19. He had been absent on day three for reported back stiffness, but a lateral flow test at the team hotel showed he was carrying the virus.
Kent gloveman Sam Billings was summoned as an emergency replacement, earning a second Test cap after his debut in the final match of the Ashes.
Billings, who will also be able to bat in the fourth innings, was England’s second substitute of the series after Matt Parkinson stepped in for a concussed Leach at Lord’s.