Prices for within-day delivery were trading at 46.90 pence per therm at 1005 GMT, down 1.70 pence since their last settlement. Prices for delivery on Monday were down 0.85 pence at 47.70 pence per therm.
With supply flows at about 274.4 million cubic metres (mcm) per day on Friday and demand expected to be about 260.6 mcm, the system was 13.8 mcm oversupplied, National Grid data showed.
Demand was down from more than 300 mcm earlier in the week and 11 percent lower than the seasonal norm of about 293 mcm, the data showed.
Forecasts from Britain's Met Office showed that temperatures were expected to reach 10 degrees Celsius on Friday and 12 degrees Celsius on Saturday, up from levels below freezing at the start of the week and usual average January temperatures of around 7 degrees.
Meanwhile, Norwegian imports via the Langeled pipeline, Britain's main sub-sea gas import route, were near full capacity at 70 mcm/d on Friday morning, National Grid data showed. In the Netherlands, the day-ahead gas price at the TTF hub was 0.43 euros lower at 20.27 euros per megawatt-hour (MWh).
The benchmark European Union carbon price dipped 0.15 euros to 7.19 euros a tonne on ICE Futures Europe.