Inspectors this week told Riverside College Halton in Cheshire that it had achieved the "quickest and biggest improvement ever in the FE sector" after raising its grades from inadequate almost across the board to good in just 12 months.
Principal Michael Sheehan said he used "tried and tested" methods to transform the college's standing after a merger left it destabilised. The experience could be a warning for colleges tempted by mergers to get out of financial difficulty, he said.
"My experience is, in the process of merger, people sometimes underestimate how difficult it can be to manage the impact it can have," he said. "People take their eye off the ball on things like success rates. It becomes all about who gets the new job and all the focus is internal."
The Learning and Skills Council is planning for a worst-case scenario where nearly a third of colleges need to merge or restructure, which could bring a greater risk of quality slipping at some.
Mr Sheehan also oversaw the transformation of Pendleton College, which was graded unsatisfactory after merging with another sixth form college in 1997. By his departure in 2004 it was outstanding, although it has since merged again to form Salford City College.
Riverside College was formed from the merger of Halton College and Widnes and Runcorn Sixth Form College in 2006. Before the merger, the sixth form college was graded inadequate, while Riverside was recovering from over claiming pound;14 million of public funds up to 1999 - a situation described by MPs as a financial "horror story".
Mr Sheehan, who arrived at the college in February 2009, said he spent a year boosting morale, monitoring students and installing an expanded student support system.
This week's Ofsted report said: "The new principal and senior leadership team have had outstanding success in bringing about positive change."
Mr Sheehan said most staff rose to the challenge, but conceded that about 40 of the 500 personnel left when the new regime came in. Expanding and strengthening senior management was essential, he said.
For students, he advocated a strong enrichment programme, offering them after-class activities that built friendships and encouraged attendance.
The college borrowed pound;2 million to improve the appearance of its scaffolding-clad campus after its pound;65 million building plans fell victim to the capital shortage.