I don't keep up with Radio 4's Book of the week but I happened to hear it announced this morning and it is a book I have actually read already, the brilliant book on Snow by Marcus Sedgwick. The page for it is here.
Bonhoeffer uses a similar phrase 'worldly Christianity'. It's J Gresham Machen that I want to line up most closely with. See his Christianity and culture here. Having done commentaries on Proverbs (Heavenly Wisdom) and Song of Songs (Heavenly Love), a matching title for Ecclesiastes would be Heavenly Worldliness. For my stance on worldliness, see 3 posts here.