Lord Hack, you've lost me.
You are surely not suggesting that someone recording marriage details was incapable of getting things out of kilter! That is, of starting (erroneously) to write the occupation in the marital condition column! Then, realizing his error, scoring through what he had written and continuing accurately!
Fireman, of course, could have been an occupation in many places of work. It might have been a firefighter but more likely to have been a person in charge of a furnace - in a train, a ship, or almost anywhere.
As for the writing - this chap wrote everything almost any which way!
Cheers,
JAP