From DEFRA
As you may see, while the birds will have enclosed accommodation as in your pic, they must also;
<<have continuous daytime access to open runs which are mainly covered with vegetation and with a maximum stocking density of 2,500 birds per hectare.>>
which is the bit we probably have in mind.
<<Egg production systems
Cage
A cage system consists of tiers of cages. The cages have sloping mesh floors so that the eggs roll forward, out of the reach of the birds to await collection. For each cage there must be at least 10cm of feed trough/bird and at least two drinkers/cage or 10cm of drinking trough/bird. Droppings pass through the mesh floors onto boards, belts or into a pit to await removal. A minimum of 550cm squared per bird is required in standard cages, which were installed prior to 2003.
Since 2003 only installation of enriched cages are allowed, with a minimum of 750cm square per bird along with a nest, perching space at 15cm/bird and a scratching area. In each cage feeding troughs must be at least 12cm/bird and at least two nipple drinkers or two cups must be within easy reach of each hen (where nipple drinkers are provided).
Barn
The barn system has a series of perches and feeders at different levels. The maximum stocking density is 9 birds per square metre and there must be at least 250cm square of litter area/bird. Perches for the birds must be installed to allow 15 cm of perch per hen. There must be at least 10cm of feeder/bird and at least one drinker/10 birds. There must be one nest for every 7 birds or 1 square metre of nest space for every 120 birds. Water and feeding troughs are raised so that the food is not scattered
Free range
In free-range systems, the birds are housed as described in the barn system above. In addition birds must have continuous daytime access to open runs which are mainly covered with vegetation and with a maximum stocking density of 2,500 birds per hectare.
In all systems the birds must be inspected at least once a day. At the end of each laying period the respective houses are completely cleared and disinfected.>>