Since taking charge of a Test side that had won one of its previous 17 Tests, McCullum has instilled a fearless brand of cricket, nicknamed ‘Bazball’, which has seen England win 19 of their 28 Tests since.
Under the New Zealander, England’s Test team scores at 4.57 runs per over on average, compared to 3.09 in their 29 Tests previously.
McCullum is also credited with being the inspiration for the style of play which saw England’s white-ball team go from an embarrassing World Cup exit in 2015 to champions in 2019.
He takes over a squad which is in need of renewal, with a number of the World Cup-winning team nearing the end of their careers.
Under Mott, who was appointed when England split the head coach roles in 2022, England won the T20 World Cup in Australia.
However, they endured a calamitous 50-over World Cup in India last year, winning only three of their nine matches.
And they surrendered the T20 title in the Caribbean and United States in June, beaten in the semi-finals by eventual champions India.
“I’m delighted Brendon has chosen to do both roles with England,” said Key. “I believe we are incredibly fortunate that a coach of his quality is prepared to commit wholeheartedly to English cricket.
“Being able to align all teams now is particularly exciting.
“For the last two years, constant clashes between formats have made it challenging for the white-ball environment; fortunately, these are easing starting from January.
“The timing of the schedule [from January] will allow him to dedicate the necessary focus to both roles.”
After the Test series ends against Sri Lanka at The Oval next week, McCullum will take a short break at home in New Zealand before joining the Test team for their winter tours of Pakistan in October and the three-match series against New Zealand in December.