“I believe their dependence on Viagra for recreational reasons, if you like, is driven to some degree by the plethora of sexual imagery through pornography which is so instantly available,” Francis explained. “This is one of the last few remaining taboos in modern society today, even in this day and age of openness, male sexual performance is one of the few matters in life which is really considered deeply confidential.”

Pressure to perform has led to dependence in some young men.

“No matter how I’m feeling, what’s going through my head, or how attracted to the woman I’m with, it makes no difference. Now, if I know I’m due to see a woman, I discreetly take two pills beforehand,” said Daniel Atkinson. “I sometimes find it hard to do without Viagra.”