Customers of the UK's leading energy supplier face a £400 rise in their annual energy bills, according to an industry expert.
The end of a price protection offer signed in 2005 by 460,000 British Gas customers could, uSwitch claims, increase their household energy bill from an average of £820 per year to around £1,194.
These British Gas customers managed to avoid the price hikes introduced by energy suppliers in 2008 when the average bill soared by 42 per cent.
It has been suggested that these customers could be unlikely to secure such a cost effective deal in the future.
Tom Lyon, an energy expert at uSwitch, said: "Whether by luck or by judgment everything fell into place for this group of customers. They fixed at the right time, for the right price and for the right length of time."
Last week, Mark Todd, co-founder of energyhelpline.com, revealed that consumers have been shocked to receive record bills of more than £500 from their energy suppliers in the past month.
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