The Cambridge researchers however, say that the irritability linked to breastfeeding is only natural, and not a sign of stress or even necessarily hunger. Instead, it is the baby’s way of bonding and seeking attention and security. 

While bottle fed babies may seem more content, they may simply have eaten too much. Like adults who comfort eat, they may have been calmed by eating, or drinking, more than they should.

In one of the first studies of its kind, the temperament of more than 300 babies was assessed when they were three months old. 

This was done by asking their mothers to answer almost 200 questions about their children from how they responded to being washed and dressed to how easy they were to get down to sleep. 

The results varied little between boys and girls, socio-economic status of the parents or the mother’s age.

Breastfeeding has been shown to help protect babies against obesity, eczema and ear, chest and tummy bugs.

Avoiding formula can cut the odds of child being a fussy eater in later life, as well as cut the woman’s odds of some cancers and help with weight loss. Despite this, Britain has one of the lowest breast-feeding rates in Europe. 

Around three-quarters of new mothers start breastfeeding but by four months, this number has dropped to just a one-third.

Clare Byam-Cook, a former midwife who has taught celebrities such as Kate Winslet and Natasha Kaplinsky how to feed their babies, said: ‘Breast is definitely best – as long as mother and baby are thriving on it.

‘But if your baby is crying and unsettled and when you give it a bottle it becomes calm and settled, then a bottle is best.

‘If you offer the baby a bottle and he doesn’t settle, then something else is the problem and the mother needs to find out what it is.’