Perhaps overall, but the article is mostly talking about the high-end market. From the reference:
> Prices falls are concentrated in the most expensive areas of London...
> The top 11 of London's 33 boroughs are down an average 7% annually...
> Kensington & Chelsea .. have fallen sharply there by 12.9% in the last year — more than £200,000.
> Prices in Camden fell 10.8%, the City of London by 18.2%, and in Wandsworth by 12.7%.
Perhaps you meant the lowest end, as this part more closely resembles your 2% drop:
> The 11 cheapest boroughs have seen a modest fall of 1.3% over the year overall...
