It was, as he puts it, "dreamland."
Long before he became chairman of the club and one of English football's most respected administrators, Sheepshanks was a teenager standing on the terraces at Portman Road, witnessing the greatest period in Ipswich Town's history unfold before his eyes.
Speaking to Football Presse, Sheepshanks reflected on those remarkable years under Robson, a spell that transformed a provincial club into one of Europe's finest sides and left a lasting impression that would shape his own football philosophy for decades to come.
What makes the story even more remarkable is that Ipswich almost never appointed Robson in the first place.
After Bill McGarry guided the club to promotion in 1968, he departed for Wolverhampton Wanderers believing he had taken Ipswich as far as he could.
"Bobby Robson was third choice," Sheepshanks revealed. "Frank O'Farrell at Manchester United and Billy Bingham at Everton were the first two choices.
"Bobby Robson was third choice for the Cobbolds, who ran the club in those days."
History, of course, would prove that decision one of the most significant in English football. Robson's first few seasons demanded patience rather than celebration.
"He came and we had four years of struggling, but we stayed up," Sheepshanks recalled. "But really, from 1973 until 1982, we were in Europe nine years out of ten."
It is a statistic that still surprises modern supporters when they consider the scale of Ipswich Town at the time.
"If there had been a Champions League in those days, I think we'd have been in it six times.
"People just can't believe little old Ipswich.
"We were absolutely one of the best teams in the land."
Liverpool dominated English football during that era, yet Ipswich established themselves among the elite, winning the FA Cup in 1978 before lifting the UEFA Cup three years later. For supporters like Sheepshanks, every season brought another opportunity to watch some of the world's finest players arrive at Portman Road.
"The treat for Ipswich Town fans was being in Europe every year," he said. "We'd see Johan Cruyff, Johan Neeskens, Antonín Panenka, Michel Platini, Johnny Rep...
"We saw these players when they were in their pomp."
Yet Sheepshanks insists Ipswich's own stars deserved to be mentioned alongside those illustrious names. He reels off the team almost instinctively, as though transported back to the North Stand.
"Paul Cooper was a brilliant goalkeeper.
"Mick Mills was captain of England.
"George Burley was a regular Scotland international.
"Kevin Beattie was one of the greatest ever players.
"Russell Osman and Terry Butcher both became England internationals.
"Arnold Mühren had the best left foot in football at that time."
Then came the forwards.
"Alan Brazil was a phenomenal striker.
"Paul Mariner.
"Eric Gates.
"They were fantastic players."
Looking back, Sheepshanks believes supporters perhaps took their extraordinary success for granted.
"We were spoiled."
That success was built not on lavish spending but on exceptional coaching, astute recruitment and a dressing room culture that Robson cultivated over more than a decade. His influence would extend far beyond Suffolk.
Robson left Portman Road in 1982 to become England manager, following Sir Alf Ramsey in making the same journey from Ipswich to the national team.
For the club, replacing a manager of that stature proved almost impossible.
"It's very hard when you lose a manager to England," Sheepshanks admitted. "We lost two.
"Alf Ramsey... and then Bobby Robson.
"When Bobby left, Bobby Ferguson carried on for four years, but ultimately the club ran out of money and we got relegated."
For Sheepshanks, watching that decline was painful. Many of his heroes departed, and the club's fortunes slipped dramatically after years competing with Europe's best.
The experience strengthened rather than weakened his attachment to Ipswich.
In 1986, frustrated by what he believed was poor communication between the board and supporters, the young businessman wrote directly to chairman Patrick Cobbold.
"I said, 'I'm a young business guy. I'm an Ipswich diehard,'" he recalled. "Essentially, your PR sucks.
"You're not telling us anything.
"All we see as fans is our favourite players being sold."
The letter unexpectedly changed his life. Cobbold eventually invited him to lunch, a meeting Sheepshanks later realised was effectively an interview.
"I figured out afterwards they wanted to know how much I loved the club. How much did I know about it?
"How many silly jokes could I tell and make them laugh?
"And how well could I hold my booze!"
It marked the beginning of a relationship that would eventually lead him into the Ipswich boardroom and, years later, the chairman's office.
But before all of that came the memories. For Sheepshanks, they remain as vivid today as they were more than four decades ago.
"What was it like to be an Ipswich supporter in the late seventies and early eighties?" he said.
"It was just dreamland."
Keep following our 5-part series with David Sheepshanks this week as part of the promotion for his new book, 'Man on a Mission'. Available here.
