Industry has most eggs in one basket

There are about 30 million laying hens on farms in this country. Eight-six per cent of eggs sold in British shops come from hens kept in battery cages. Many are euphemistically marketed as "farm-fresh" or "country" eggs, in cartons illustrated with idyllic rural scenes.

11 per cent of eggs come from free range hens, which means they have continuous daytime access to outdoor runs covered mainly with vegetation. The maximum stocking density is 395 birds per acre.

Three per cent come from "barn" or "perchery" hens, meaning the birds live in a barn which incorporates a series of perches and feeders at different levels.