Prices for within-day delivery were trading at 56.20 pence per therm at 0940 GMT, up 1.15 pence from their last settlement. Prices for delivery on Friday were up 0.90 pence at 56.00 pence per therm.
With supply flows at about 229.7 million cubic metres per day (mcm/d) and demand expected to be about 254.9 mcm, the system was 25.2 mcm undersupplied, National Grid data showed.
Norwegian imports via the Langeled pipeline were down by around 10 mcm/d on Thursday morning, according to National Grid data.
Langeled is Britain's main sub-sea gas import route with a total capacity of around 70 million mcm/d.
The drop in flows through Langeled was a result of an unplanned outage at Statoil's Troll field off Norway.
Gas output from the field will be reduced by 16 mcm/d on Thursday due to maintenance, which is expected to last for three weeks, gas system operator Gassco said on Wednesday.
Further along the curve, gas for December delivery was up 0.70 pence at 55.95 pence per therm, while the January contract was up 0.43 pence at 56.85 pence.
In the Dutch TTF gas market, day-ahead prices were up 0.30 euros at 23.10 euros per megawatt hour. They were also pushed higher by the drop in supply from Norway.
In Europe's carbon market, benchmark EU Allowances (EUA) was down 0.08 euros to 6.96 euros per tonne.