Help Me ID This 1960's British Movie!

I saw this flick on late night TV, and I haven’t been able to find it.
It was extremely funny, and I would like to see it again.
What I remember of the plot:
-A young man is sent by his company, to Sicily, to scout out a location for a big new oil refinery.
While in Sicily, the man runs afoul of the local mafia-and the people he is trying to do business with keep getting murdered. His local guide keeps telling him that they all died of “a heart attack”. Finally, he and the guide are in an outdoor cafe-and a mafia hit man is taking pot shots at them.
Anybody remember the name of this movie?

Is it Meglio Vedova/Better A Widow?