I'm not really surprised...pax figures have rocketed since three flights daily were introduced and the new increased tax on long haul flights will surely encourage traffic via BRU/AMS/CDG and DUS, this leg just having a £1 increase.
Not sure what effect this will have on Dubai connections.
I find it difficult to grasp the thought processes in the Treasury which managed to arrive at a policy likely to inflict such damage to the UK aviation industry. Maybe they have never heard of the law of diminishing returns.