The 38-year-old took Posh from npower League Two to the Championship in successive years during his first spell in charge but left in acrimonious circumstances in November 2009 with the club bottom of the second tier.
A poor year in charge of Preston followed for Ferguson - where he was sacked after Christmas - while chairman Darragh MacAnthony has seen Mark Cooper, Jim Gannon and Gary Johnson try and fail to emulate his success with the League One side.
Johnson was the latest to depart on Monday but after a 2-1 win over Brentford on Tuesday night lifted Posh up to fifth, Ferguson is confident of an immediate return to the Championship.
"You'd have to say automatic promotion is still possible this season. Anyone who can go on a run has got a right chance," he said. "I know the saying is `never go back' but I don't believe in that.
"I've missed the place. I've had a hard 12 months at Preston but it's good to be back. We want to get into the Championship and stabilise in the Championship. That has always been the aim."
Source: PA
Source: PA