Well funny that, just over 2 years ago I was a pax sitting at the Very rear of a BA757 (Reg ended in ER, Wonder if its the same plane) from LHR to CDG. A few moments after take off a strong smell of burning was noticed throughout the cabin. Within a few minutes the captain came over the PA and said we would be returning to LHR cos of a tech glitch. Almost immediately after that he came over again and said he was taking precautionary measures to land in LGW as it was easier to make an immediate landing. Pilots were on O2 and we made a full emergency landing!!! Sounds like the same thing has happened again. The reason given for my incident was that the a/c was just out of heavy maintenance and there must have been dust burning...."DUST anyone??? DUST DUST I JUST LOVE A BIT OF DUST"!!!!!!!