In those 20 years olive oil has gone from a £2m market to an £80m one. But Filippo Berio UK country manager Walter Zanré recently alerted the trade to "worrying" Nielsen data which showed category growth overall had slipped in volume and particularly in value, down from 10.7% to 1.1% year-on-year in December.
"Contrary to expectations the substantial reduction in retail levels for own label products has not increased consumption levels but has simply had the effect of devaluing the category," he said.
"Mind you," Zanré adds this week, "when you consider that many of the major grocery categories are stagnant, volume growth of 6% is still positive. But before, we were spoilt.
"Olive oil is a category that is not so price-sensitive as others. You need to do something else to drive volume than just cut prices."
Yet even with extra virgin in the relative doldrums, Filippo Berio UK says it is bucking the trend with significantly higher growth levels than the overall category. And the Mild and Light variant it has vigorously pushed is gaining a growing place in British cooking.
It all began when Salov, the Italian producer owned by the Fontana family, placed an ad in the February 19 1983 issue of The Grocer seeking a UK distributor.
RH Amar director Henry Amar recalls: "Two of our directors had been to IFE 83 to find a high quality supplier of olive oil and had not met anyone who fitted the bill.
"Back at the office, the directors read The Grocer, saw Salov's advertisement and I wrote to their export director, Alberto Fontana. Such is the pulling power of The Grocer, Salov received 25 replies to its ad. Alberto Fontana had heard of us as major table olive suppliers and put us on his shortlist."
On meeting, the men hit it off with a remarkable likemindedness. "We had lunch together at a restaurant in Chelsea. Our discussion went so well, he gave us his distributorship there and then. He simply announced ­ I have made up my mind'. An extremely unusual thing to happen."
This immediate rapport was permanent. Henry and Alberto had in common a passionate family pride, a devotion to their companies, and a sheer relish in doing business ambitiously, and energetically.
"Salov is totally market focused and very enterprising. But it has been friendship as well as business, and that has been very important to us," says Amar, who still speaks to Fontana by phone every day.
Back in 1983, Amar was soon highly impressed by Salov's versatility and determination.
"Sainsbury decided to take on olive oil, but wanted bottles ­ it was all in tins then ­ which Salov hadn't done before. I was astonished by the speed with which Salov got a bottle line and the labels up and running ­ within two or three weeks."
This year Salov opens a new factory at Viareggio boosting capacity from 80 million bottles a year to 200 million. "It is a fantastic new factory in a beautiful site," says Amar.
"Our relationship has been so enjoyable. It has been tremendous fun building a new category, and satisfying to hold our position in the face of massive assaults by the competition. But olive oil is special and needs a specialist."