Awesome photo.
IDK anything about tanks at all other than what I read on wikipedia in the last few minutes.
This looks like a British Heavy Tank Mark IV but I'm happy to be corrected.
Some wikipedia stuff:
The hull was undivided internally; the crew shared the same space as the engine. The environment inside was extremely unpleasant; since ventilation was inadequate, the atmosphere was contaminated with poisonous carbon monoxide, fuel and oil vapours from the engine, and cordite fumes from the weapons. Temperatures inside could reach 50 °C (122 °F). Men sometimes lost consciousness inside the tank but more often collapsed when getting out into fresh air. The symptoms were suggestive of carbon monoxide poisoning but the high temperatures inside together with humidity were also identified as a possible cause.
Sounds pretty awful.