She was introduced to the trattoria, which is tucked away off one of Bologna's main streets, through the Calori family, owners of Barbour's Italian business partner, W P Lavori, based in the northern Italian city.
"Whatever business we may be discussing in their offices, everything stops at 12.30pm for lunch, and we decamp to Sandro's," says Barbour. "All our important decisions and agreements have been reached around the luncheon table at Sandro's."
The trattoria makes its own pasta daily, with the butterfly-shaped tortellini a speciality. Other favourites include foglia morta, thinly sliced veal served with fresh rocket, and rabbit cooked in balsamic vinegar. When Barbour notched its centenary in 1994, Sandro's was the venue for celebrations with the Italian partners. They were served wild mushroom risotto in a lattice basket of Parmesan cheese.
But Margaret says: "I have never been shown a menu. Nor have I seen a menu consulted. The customers either know what they want, or rely upon the advice of Sandro and his team.
"The food is always accompanied by lively conversation, which inevitably comes back to business."
One of her special pleasures when visiting is watching the preparation of the trattoria's special dessert of vanilla ice-cream flavoured with balsamic vinegar.
However, she has had to learn to control her expressions of gastronomic delight. As she explains: "On an early visit, after commenting on the quality of the Parmesan, I found myself with a chunk that was big enough to put me seriously over the excess baggage limit."
Antica Trattoria Da Sandro al Navile, Via Del Sostegno 15, 40100 Bologna (Telephone 00 39 051 634 3100)