Two goals by Uwe Rosler, the German striker Royle once tried to sign for Everton, and a third by the substitute, Lee Bradbury, underpinned a performance of renewed determination from a team who had seemed to be sinking under the deposed Frank Clark. But Royle is the first to acknowledge the enormity of the job he has taken on.
"We're not getting carried away," he said afterwards. "There have been too many false dawns at this club. But I was confident when I came that we can avoid relegation and that confidence has been swelled this afternoon.''
Royle has likened his role to that of a firefighter. With the flames of relegation already licking at City's boots it seems an apt description and while suspicion remains that he has opened the door on a conflagration that would send even Red Adair into retreat, Royle's record in saving Everton from the drop and keeping Oldham in the top flight for three years entitles him to such self-belief.
He has 14 matches in which to stop City from tumbling into the uncharted reaches of the Second Division. Even should he succeed, however, it may be too late to preserve the reputation of his chairman, Francis Lee, whose hold on power at Maine Road looks increasingly tenuous.
Lee, once revered as a City player, has seen his stock fall so low in high office that he is reviled in some quarters with the intensity of feeling once directed at his predecessor, the late Peter Swales.
"If there was a cup for cock-ups," Lee once famously remarked, "then City would have a full trophy cabinet every year." After the clumsy manner in which Clark was replaced, hearing his fate on local radio, the statement appears as true today as ever.
Royle is the club's seventh manager during Lee's time, which for a man who promised to end the revolving door policy characteristic of the previous regime is an extraordinary record. Mid-table in the Premiership when Lee took the reins, City have seen Brian Horton replaced by Alan Ball, Asa Hartford, Steve Coppell, Phil Neal, Clark and now Royle in reaching the lowest league position in their history. The list does not include Dave Bassett, who accepted the job, slept on it and then changed his mind.
Lee, who last week handed the day-to-day running of the club to Dennis Tueart and Michael Turner, the chief executive, needs Royle to succeed more than any of his predecessors. With the Cheshire businessman Stephen Boler's 24 per cent holding up for sale, Lee is facing a battle for control involving several counter-bids and attempts to rally financial support are unlikely to bear fruit if Royle fails to deliver.
At least there was an encouragement for him yesterday, when City at least displayed the commitment they will require in the weeks ahead.
Aided throughout by the uncertainty of Swindon's teenage goalkeeper Steve Mildenhall, they were rewarded in the 23rd minute when Rosler forced the ball home from close range. Steve Cowe headed a deserved equaliser for Swindon with 20 minutes left but then Rosler pounced for his second after a neat move involving Bradbury and Jim Whitley before a looping header by Bradbury made sure it would be Royle's day.