Pint-sized Cockney Ling replaced Gary Brabin on the Cambridge bench at the end of last term after the outgoing manager had fallen out with Nick Griffin lookalike Rolls.
The fiery Rolls had been widely criticised by fans for driving a World War II tank through Brabin's back garden after United's Conference play-off final defeat against Torquay.
Ling quashed concerns that his pugnacious personality would clash with the megalomaniacal Rolls asserting: "I've got a three-year contract and we see this as a long-term agreement."
Nine days later, after a friendly defeat against precocious local rivals Histon, Ling quit when Rolls put a deadly redback spider in each of his shoes.
However, the departure of Rolls has opened the door for the return of the ex-Leyton Orient man.
"It's obviously an emotional moment for me coming back to a place I have come to see as home," Ling told journalists.
"I can promise the fans that I have even more to offer. I'm not one to make promises I can't keep, but I expect to be here long into September."