Question to the Department for Business, Energy and Industrial Strategy:

To ask the Secretary of State for Business, Energy and Industrial Strategy, what information his Department holds on the proportion of customers of (a) British Gas, (b) EDF, (c) E.on, (d) Npower, (e) Scottish Power and (f) SSE who have been on that company's standard variable tariff for more than (i) three, (ii) five and (iii) 10 years.

The Department does not routinely collect information on the proportion of customers of energy suppliers who are on a company’s standard variable tariff.

The Department holds data on the proportion of each of the six large energy suppliers’ customers who were on standard variable tariffs in March 2016, but it does not hold information about the length of time customers have been on those tariffs.

The information held by the department was provided by the regulator Ofgem pursuant to its statutory functions of providing advice, information and assistance to the Secretary of State on request (section 34(4) of the Gas Act 1986 and section 47(3) of the Electricity Act 1989). Insofar as the data relates to particular energy suppliers my department is restricted by section 105 of the Utilities Act 2000 from disclosing it except in accordance with that section.