Gareth Ainsworth has left Wycombe Wanderers after more than a decade in charge to become head coach of Championship club Queens Park Rangers.
He will be replaced at Wycombe by Colchester boss Matt Bloomfield, who has “agreed in principle” to return.
Bloomfield, 39, left Adams Park in September to take charge of the U’s.
Ainsworth spent almost seven years as a QPR player before joining Wycombe in 2010, becoming their manager two years later.
Before his exit from Wycombe, he was second in the list of longest-serving managers in England’s top four divisions.
‘Absolutely rocking’
Only Harrogate’s Simon Weaver had been at the helm for a longer period than Ainsworth, who leaves the Chairboys seventh in League One, just three points outside the play-off places.
“This is all a little bit surreal. It has been a whirlwind two days and leaving Wycombe Wanderers was very tough because of the connection there,” he said.
“But this is QPR and when I spoke about something special forcing me away from Wycombe, this was pretty special.
“This is going to be a real challenge because the club is so special to me, and so huge as well. I want to get Loftus Road absolutely rocking again.”
Ainsworth is QPR’s third full-time head coach this season.
Michael Beale started the campaign in charge before leaving to take over at Scottish Premiership club Rangers in November, followed by Critchley’s short reign which began with a win at Preston on 17 December.
That result saw QPR climb into the play-off places, where they were for much of the first half of the season.
But after a winless league run of 10 games, the London club are now 10 points adrift of the top six and only eight above the relegation zone.
Ainsworth’s assistant Richard Dobson and analyst Josh Hart will be moving from Wycombe with him.
More to follow.