This London company was set up in 1992 and is now led by chief executive Dr Pete Calveley, 57, a former police surgeon. It oversees 200 nursing homes, caring for 11,000 people and offers dementia care and assisted living along with support for younger people with disabilities. With a workforce of 15,462, it is the biggest employer on the league table. In July, it was reported that the business had been put up for sale at £2.5bn.