Reverse magnetised

A few weeks ago I saw that the compass that travels daily in my rucsac had become reverse magnetised. Luckily I was in a field and could compare with my watch and the sun. It might have been more serious on a hillside.

Apparently this is quite common now and believed to be due to the strong magnets in the speakers of the devices we carry. Certainly I often carried the compass next to a mobile phone and camera.

I've read that Silva will remagnetise the needles so I've sent them an email. Although I understand the theory I'm not going DIY as it seems like an accident waiting to happen.