Probably a combination of 2 morons and poor discipline by myself, but A1M, stupid woman out in 2nd lane doing 65, BMW behind me doing roughly the same speed (75-80), I pull out to lane 3 to get round stupid woman who can't use a motorway, check inside mirror to pull back , begin moving over, quick blindspot check at last minute before moving back into lane 1 only to find BMW driver undertook lane hogger and sped up, and was level with me.. Prick!