Want the cheapest energy deals? You could be out of luck – suppliers can now exclude you from getting their best tariffs

A few weeks ago, an interesting energy tariff came through from First Utility. It was a reasonably priced one-year fix, costing on average £812 a year with what regulator Ofgem calls typical use – by no means the cheapest, but still good value. What made it interesting was the offer of £2.50 per fuel, per month off...