When was standing charges first added to gas and electric bills?

Standing charges have been applied to utility bills for decades in the United Kingdom. Before privatisation in the 1980s, the gas and electricity industries charged based on consumption and a small rental for the meter. Once the industries were privatised, however, a fixed standing charge for electricity was first introduced by some regional electricity companies for prepayment and economy 7 customers in June 1997.[1] Standing charges for gas came later after privatisation; originally based on meter size they would apply regardless of energy use.