* Within-day gas price up 0.40 pence at 51.00 pence/therm at 0857 GMT.

* Day-ahead gas price up 0.35 pence at 51.00 p/therm.

* Traders said forecasts had changed to signal colder-than- expected temperatures on Thursday, increasing expectations of demand for gas which heats around 80 percent of Britain's homes.

* Average temperatures in Britain were expected at 5.9 degrees Celsius, 1.6 degrees lower than initially forecast, Eikon Refinitiv data shows.

* The lower temperatures have led to an increase in expected local distribution zone gas demand to 224 million cubic metres (mcm) from 212 mcm the previous day, Refinitiv analysts said in a daily research note.

* Gas system undersupplied by 3.8 mcm with demand forecast at 296 mcm and flows at 292.2 mcm/day, National Grid data showed.

* Forecasts of stronger output from the country's wind farms on Friday was expected to curb demand for gas from power stations.

* Peak wind power generation is forecast at 8 gigawatts (GW) on Thursday and will rise to almost 12 GW on Friday, National Grid data shows.

* Further out on the curve prices were also higher.

* March contract up 0.95 p at 51.35 p/therm.

* Summer 2019 contract up 0.55 p at 48.10 p/therm

* Day-ahead gas price at the Dutch TTF hub up 0.05 euro at 19.05 euros per megawatt hour.

* Benchmark Dec-19 EU carbon contract up 0.19 euro at 23.89 euros per tonne.