In recent months Mr Turberville, a 45-year-old Aberdeen-born accountant, has taken to the road in a battle bus touring filling stations from Sweden to Spain. "Did you know that in Norway we serve 80 million hamburgers a year in our shops?" he asked. We confessed we did not.
His school of management is light years away from the old Shell doctrine. "Our business performance has not been acceptable. We've fallen into the trap of taking the customer for granted," he admitted, grasping a leaflet from the one of the companies he most admires, the rapidly growing Pret a Manger sandwich chain.
Mr Turberville fought against Shell's agonisingly slow decision- making machine. "You'd wait weeks to have something agreed by someone who hadn't seen a customer in months," he explained. Under the new structure, eight or nine layers of senior and middle management would be replaced with three.
The new approach has put staff back on the forecourts. Mr Turberville believes oil companies "automated the hell" out of garages in the 1980s.
"Like lemmings we all followed that," he said.
But the strategy is risky, depending on the improved service standards pulling in more customers. Sales at one west London filling station are up 15 per cent in trials of the changes, but Shell admits some sites are far less profitable than others.
At least yesterday Mr Tuberville had God on his side. As he walked on to the petrol station forecourt an elderly nun approached him, congratulating Shell on the way a team of employees was washing her Mini. "What did I say? It's working," he beamed.