power producers don't buy at wholesale prices, they have a whole different category of pricing - see below from DUKES (
Dukes 1_7.xls). The final figure is for 2012, so ok it's not bang up to date, but AFAIK this is the actual figure for the actual price paid in that year for the gas burnt whether supplied from a long term or short term contract..
What focusing on the base price alone of gas misses though is the proportion of electricity generated from each fuel. Last year the price rise in gas was offset to a large extent by switching a big proportion of generation from gas to coal.
This year this will inevitably reverse due to the closure of 3 x coal fired power stations in April, plus the impact of Osbournes carbon tax on coal prices in particular, so we're now feeling the 50% price increase in wholesale gas this winter that was effectively buffered by the switch from gas to coal last winter.
So it does annoy me when people almost excuse the lack of any proper detailed analysis of the situation by the press or politicians by saying that the figures don't exist - pretty much all the data you could possible want is published annually in DUKES at least to get a reasonable overall picture of the situation, though it doesn't break it down for each individual company. The problem is lack of any journalists or politicians prepared to actually do some basic research for themselves beyond reading a press release / summaries of the documents involved