Palmerston, the Foreign Office cat, has returned to work after six months recovering from stress caused by civil servants constantly picking him up and overfeeding him.

Those working in the department have been warned not to touch the cat unless approached, and to stop feeding him treats.

In July, the cat was taken to the house of Sir Simon McDonald's Private Secretary in order to recover from stress; the mouser was overweight and had groomed all of the hair off his front legs.

Sir Simon, a senior civil servant, is in charge of Palmerston's well-being and on Monday morning issued a strict letter to staff, warning them that if they do not change their behaviour towards the cat, he may be retired for good.

Mystery has surrounded Palmerston's extended break, with some worrying the cat was gravely unwell and close to death.

However, these rumours were unfounded and the animal is happy and back to full health.

The letter reads: "He is happy, healthy and full of energy. His pelt is glossy and mostly grown back (over grooming is, I’m told, a similar habit to human’s nail-biting; the habit can take a while to kick). His diet is regulated and free of Dreamies. We need now to keep him that way!"