09L and 27R are the same runway but just in opposite directions. I've drawn out a diagram and for some reason the TORA for 27R is 18m less? Where has that 18m disappeared? I've been trying to work out the difference in values using only the information in the table and I still feel that 27R should have a TORA of 3902m (the same as 09L).
These seem to be the numbers of Heathrow / EGLL. When you look at the taxi diagram, you see that on 09L you have a taxiway that places you right at the beginning of the runway whereas on 27R when taxiing on A1 you end up juuust behind the start of the runway – probably 18m behind it.