"This is the worst flight I have ever been on. We were stationed on the runway for over one hour in 35c stagnant heat(The captain announced this temperature over the speakers) with no air conditioning with fumes in the cabin. Everyone in the back of the plane where I was literally had sweat dripping off them and my t-shirt and jeans were soaked with sweat. Luckily I had a change of clothing in my carry on bad so I did not have to arrive stinking in Sydney like everybody else. It took the staff 45 minutes to offer us a glass of water. This however should be no reflection on the staff who were well mannered and very friendly, but a reflection in the breakdown of communications between the captain and the head of staff. The captain of the flight came on after 30 mins and announced that he was caught in traffic due to the floods in Bangkok and that was the reason for the first 30 minute delay, so I ask why were we boarded on to a plane with no air conditioning when you knew the captain was going to be 30 mins late? Then after 30 mins there was some issue with the engine not starting and the cabin where I was down the back began to smell like lighter fluid while they tried to restart one of the engines, all in 35c heat.An utter disgrace will never fly BA again."