It all looks quite damning, until you read on. In October 2014 the police launched an operation to combat the rise in violent crime across the capital, specifically targeting licensed premises after research suggested they were hot spots for violence. The Met has stated that the rise in recorded offences can be partly explained by this crackdown "rather than a rise in violence per se". The British Beer & Pub Association point out that these figures cover 23,500 licensed premises in London, and sensibly state they'd want more evidence before concluding there was an upward trend.
It's good that the police are chasing up violent crime with more vigour, especially in the context of major reductions in funding, but to depict the predictable rise in detection of incidents as an actual rise in the number of incidents is misleading, if not downright mischievous, especially when the police themselves have made that very point. It is particularly disappointing that the deceptive headline was in a journal that calls itself "the industry's oldest and most-respected magazine", supposedly on the side of the licensed trade.