This forum is about wrong numbers in science, politics and the media. It respects good science and good English.
I had to read the charts multiple times before I could say that you were right. The way they worded it was nicely open to be interpreted to mean something else.
A strange comment at the start of the article:
"Efficiency has always been a strange critique given that the fuel driving turbines - wind - is free."
You'd think that a 'business reporter', even one that works for the BBC, might be a bit more economically literate when discussing wind energy. The fuel might be nominally free, but you still have to build an expensive machine to get at this fuel, and the more efficient the machine is, the better the return on your investment in building this expensive machine. It might also be argued that wind isn't a free fuel. Most windfarm developers are I believe renting land from farmers or landowners, and what they're doing to a large extent is renting the volume of air above the land, this particular volume of air having the attribute of a reasonably high average wind speed.
The main thing that interested me about the article is the figure given in the table for UK installed wind capacity, 12440 MW. That figure is a bit higher than I expected - as I remember it the UK wind capacity was only about 4400 MW when the Coalition government came to power in May 2010. With the Lib Dems in charge of DECC, wind turbines appear to be being built at a rate several times higher than what was happening with the previous Labour government. After further checking with Wikipedia that 12440 MW figure is for the end of 2014, so it may be somewhat higher than that after several more months.
The impression that you get from the UK left-liberal media is that the current Coalition government is less Green-leaning than the previous Labour government. The phrase "greenest government ever" that David Cameron promised when the Coalition came into power is mentioned just about every week by somebody on the BBC News channel, but is almost always referred to sarcastically.
I think what's different about the Coalition government's period of office is that you now hear much more scepticism of Greenery from politicians. When Labour was in power anti-Green dissent was almost invisible, and the opposition under Cameron was encouraging Labour to be even more Green-leaning. The left-liberal media is spooked by the more visible dissent of the past few years rather than taking note of such things as there being a lot more wind turbines installed.
According to the BMReports web site the current "Metered" wind capacity - which I assume means that which is traded in the Grid's market from installations registered to the market - is 8403MW.
It has shown that number for quite some months now. It seems only to change when a new large development officially joins the grid.
Actual output is, of course, much lower than the maximum metered capacity.
As I type the report is suggest current Wind output is 315MW.
The peak output yesterday was about 3200MW.
The forecast peak for today is 3137MW (at 13:00 hrs) and the peak for tomorrow suggests 5137MW (at 23:00 hrs).
I assume the missing 4000MW will be private or corporate installations and a few large developments not yet officially metered.
Either that or the information provided is suspect but given that it is part of the Electricity trading system (afaik) that would be worrying.