OAPs face hardship despite gas cut.
But the charity argued the announcement was only a "small step" in lifting pensioners out of fuel poverty.
British Gas said the reduction in its standard tariff would come into force on February 19 and would affect 75% of its customers - or 7.5 million homes.
The energy supplier estimated the price cut would save customers pounds 79 on the average household gas bill.
The firm said it had made the move after "unprecedented volatility" in the wholesale gas market.
Mervyn Kohler, special adviser for Help the Aged, welcomed the move but said: "This is just one small step on the long road to lifting the one in three pensioner households out of fuel poverty.
"Even with this reduction, a high number of older people will still face some frighteningly high fuel bills.