I don't think "coffin" is a good description. As far as I know, no-one died in them. But they offered no roll over protection at all.
There was questionable weather protection too as the doors did not seal and water could get in. The back did not really protect the drivers back and that could get very wet.
They were usually lined with sacks and the driver had to wear a heavy coat on cold days. No heater or radio.
But they were better than sitting out in the open.
I once had to repair a New Performance Super, fitted with one of these cabs, that had been fire damaged.
It was in the days of stubble burning after harvest and this farm burnt fields by driving round the field with a burning tyre on a chain behind the tractor.
The driver turned too sharply on one run, catching the chain on the tyre lug and flicking the burning tyre up into the cab with the driver!
He got out with two bruised shoulders as he went through the door but suffered no burns even though he was wearing just a light shirt.
