Ask yourself where the toughest mission fields of the 20th century have been, and you might well think of various distant foreign locations.
But while many of your guesses might be correct, you could easily overlook one of the hardest areas of gospel endeavour in Britain over the last 50 years - and you might be surprised by its location: the world of England's top public schoolboys.
'The schoolmasters on whom the work depended were in a tougher situation spiritually than many pioneer missionaries,' recalls David Fletcher, a recently retired Anglican clergyman who spent many years in a ministry to pupils from some of England's most exclusive educational establishments.
