A record 4.2million patients are on waiting lists for procedures such as hip replacements and cataract removal - up 56 per cent in four years.

This represents about 1.1 per cent of hospital admissions, including day cases such as hernia repair and cataract removal, but not operations that were cancelled for medical reasons.

Patients may experience more pain, a longer recovery period, and less improvement in visual acuity than a patient with an uncomplicated cataract removal.