Lindsey Hilsum, UK C4's chief international reporter, has been in Northern Cameroon, where Nigerian activity appears to be pushing Boko Haram across the international border - which straddles the local tribe, numbers of whom are with Boko Haram.

There is a six minute fim clip:https://www.youtube.com/watch?v=SKSWiKzC4P0

Her written report:http://www.theguardian.com/world/201...ith-boko-haram