The discovery marks an important advance in theoretical physics. The existence of magnetic “charges” has been predicted for nearly 70 years but has never been observed in practice.

The study was led by Professor Steve Bramwell, of the London Centre for Nanotechnology. He said: “It is not often in the field of physics you get the chance to ask, ‘How do you measure something?’, and then go on to prove a theory unequivocally. This is a very important step to establish that magnetic charge can flow like electric charge.”