Free-range eggs are laid from hens that have the opportunity to go outside.

One different factor from hens is age.

"Most consumers still think eggs come from hens who walk around with their little chicks following in a row," she said.

The virus is not transmitted from hens to their eggs.

But this organism has recently flourished because it can now be transmitted from hens to the yolks of intact eggs.

Still, perhaps 95 percent of the country's eggs come from caged hens.

The eggs are from caged hens fed with what the company calls a "whole-grain diet" free of antibiotics.

A major supermarket chain recently told me that a quarter of its egg sales are now from hens other than battery-produced.

Besides, these eggs do not come from free-range hens, as some may be tempted to believe.

British consumers are able and willing to buy eggs from free-range hens.