Webster struck in the 77th minute to level the scores and then David Blair kept his cool in the eerie atmosphere of a spectatorless ground to kick the match winning conversion.

The fans were unable to attend because of the difficulties in moving the snow and ice in the vicinity of Murrayfield. The game had been due to go ahead on Sunday, but was postponed a day because of the snow.

The home win severely dented Castres hopes of closing the gap on Northampton Saints at the top of the Pool and with two games left to play they are six points adrift. That means they must win their final two fixtures, the last of which will be against Saints in France.

Castres got off to a flying start with a fourth minutes penalty from outside half Pierre Bernard, but it wasn't long before Edinburgh edged in front. Chris Paterson missed with his first kick of the day, but then added the extras to the first of three home tries from wing Tim Visser.

The Frenchmen hit back almost immediately with lock Rodrigo Capo Ortega charging over from a close-range forward drive to score a try which centre Seremaia Baikeinuku converted to put Castres back into the lead.

With neither side afraid to try their hand it was another free-flowing game and Visser's pace and power continued to cause problems for the visitors. A great run down the right saw him cut down just short, but still able to off load to fellow wing Lee Jones, who raced in for his first competitive try for the club.

That try ensured Edinburgh headed into the break 14-10 to the good, thanks to Paterson's conversion, and Blair extended the advantage with a penalty seven minutes into the second half following his full back's substitution through injury.

Plunging temperatures and a raft of replacements disrupted the flow of the game for both sides and it wasn't until home scrum half Greig Laidlaw was sent to the sin-bin for failing to retire 10 metres quickly enough at a penalty in the 65th minute that another score came.

Castres turned the screw and after earning a number of penalties at a series of power scrums were awarded a penalty try by English referee Wayne Barnes.

Baikeinuku added the simple conversion to level the scores and then replacement scrum half Sebastien Tillous-Borde somehow managed to squeeze his way over the line from close range to grab the lead for the visitors with eight minutes left to play.

The only consolation for Edinburgh was that the conversion was missed, leaving them with one last shot at glory. It fell to Webster to make the difference, the wing scoring a trademark kick and chase try that allowed Blair to kick for victory.