In a recent link the phrase "It's a good job that..." is used. I take it to mean the same as It's a good thing that ... but I've never in my almost 50 years of english heard job used like that before. Word-wise it makes no sense to me that it even came into being. In what part of the world is that expression used, and how did it get started?
The OED’s definition 5 of job is ‘A state of affairs, a situation, a set of circumstances. Frequently with modifying adjective, as bad, good, etc.’ The earliest citation supporting this definition is from 1690:
The first citation of good job is from Gilbert and Sullivan’s ‘Trial by Jury’ of 1876, which helpfully illustrates both that sense and the sense of ‘a piece of work’:
The origin of job itself is uncertain, but it is possibly related to the word job meaning 'a cartload; the amount that a horse and cart can bring at one time.'