The gap between the cheapest and most expensive tariffs has increased by 32% in the last year.

That’s according to new analysis which compared the difference between the cheapest tariff on the market and the average Big Six standard variable tariff which is paid by 70% of customers.

It showed a rise from £232 in December 2014 to £305 in December 2015.

First Utility estimated almost three quarters of the population who haven’t switched tariffs or suppliers missed out at least £750 per household in the last three years – enough for a family break to Disneyland Paris.

Ed Kamm, Chief Customer Officer at First Utility said: “For too long the Big Six have been exploiting their disengaged customers by keeping them on their most expensive tariffs – despite the huge savings available for those who switch. The fact that most households could have saved enough over the last three years to treat the family to a break at Disneyland shows they’re taking the Mickey.”