Kelly worked with Rams boss Billy Davies at Preston but was blocked from joining the Scot at Pride Park last summer and placed on gardening leave.

"I know what David can bring to this club and that's why I'm delighted to have him on board," said Davies.

"With the greatest respect to my staff, I said I felt I had managed last season without my right arm. Now I have my right arm back."

Davies masterminded Derby's promotion to the top flight through the play-offs but there was speculation he was set to leave, partly because the Rams had not landed Kelly.

He allayed those fears by signing a new deal at the club, but had all but given up on getting Kelly to the club and had started to look elsewhere for a number two.

However, new chief executive Trevor Birch's involvement in discussions helped pave the way for Kelly's arrival and Davies was quick to praise the chief executive.

"I genuinely thought it wasn't going to happen and it wouldn't have happened if people (Birch) had not done what they are very good at, which is bringing normality to proceedings," Davies added.

"David is a tremendous lad to have around, whether in the dressing room or on training ground.

"When you get to Premier League level, it is very important to have the right amount of hands on deck.

"It is very important to get the staffing structure at the club right."

Kelly, who is not allowed to comment on his former employers, is delighted to be back involved in the game.

"It's been a long time coming, but I'm glad to be here," he said.

"In the meantime I've watched lots of football, played lots of golf, and I've had a good year. It wasn't frustrating. The situation was what it was, and I just got on with things. I'm just happy it has been sorted."