I've been doing some research on this area, and have hit a snag. Two different reputable sources quote two different numbers for tanks present at Fleurs in 1916 (the baptism of fire).
Fire-Power by Shelford Bidwell & Dominick Graham say out of 49, 32 reached the start, 9 broke down, 9 failed to rendezvous with infantry and 9 reached their objective.
David Fletcher in Tanks and Trenches says 36 arrived at the start line out of 49 tanks, and gives a variety of info on the breakdown (so many from C, so many from D - in each Corps etc).
Can anyone confirm the numbers that were on the start line?
My list on Landships Google, based mainly on Trevor Pidgeon's "Tanks at Flers", indicates 36 of 48 tanks made it to the start point, 34 started and 23 engaged the enemy.
The actual figures will vary a little depending upon what the writer is counting as the start point, started etc.