Chief Executive John Williams announces the news

The Manchester United assistant coach, has put pen to paper at Ewood Park after discussions with the club earlier on Thursday and has signed a contract which will take him to June 30, 2002.

Kidd will not assume his position until after Saturday's clash against Charlton, but will be introduced to the crowd by chairman Jack Walker.

The BBC's Mark Jones discusses Kidd's appointment

Walker said: "I'm delighted Brian has decided to join us - he was always our first choice."

After over seven years at Old Trafford, Kidd admitted it was time to move on and United's chief executive Martin Edwards said his departure would be a big blow.

"He wants to progress his career and he wants to have the chance of being a number one," Edwards said.

Fergie pleads with Kidd

Ferguson had been keen to hang onto his loyal lieutenant, and had earlier stated: "We do not want to lose Brian. He is very important to United.

"We have built up an excellent staff and Brian has been a key part."

United initially rejected Rovers' approach for Kidd, who has been Ferguson's right-hand man for almost eight years.

Kidd has long been tipped, along with Middlesbrough boss Bryan Robson, as a possible successor to Ferguson when the United manager decides to retire.

'One of the world's best coaches'

Former United star Nobby Stiles, who played with Kidd in the 1960s and then worked with him on the coaching staff, believes he would be a big hit at Ewood Park.

"Kiddo is one of the top coaches in the world," Stiles said.

Kidd was on the scoresheet when United won the European Cup in 1968

"I worked with him for two years before he stepped up to become assistant manager and I saw at first hand how good he is with the players.

"He's got a great sense of humour and he can make people laugh, even in the most serious moments.

"He's also been everywhere to all the big clubs like Juventus, Inter Milan and Ajax and the great thing about Kiddo is that he is always willing to learn.

"In a way it's nice for him to see that other people want him and appreciate him but Blackburn's gain would definitely be United's loss - I've no doubts about that.