[Truncated abstract] This work aimed to contribute to a gap identified by Stubbs (2007, p. 182) and Wray (2012, p. 244) relating to the communicative purpose or discourse function of multiword expressions. Drawing on Goldberg's (2006) definition of a construction, the work differentiated between lexicogrammatical combinations that achieve constructional status by virtue of the fact that they
are in some regard non-predictable, and fully predictable lexicogrammatical combinations that achieve constructional status by virtue of frequent use. The work focused on expressions in which non-predictability, rather than frequency of use, was a defining feature.
Corpus linguistics has extended the understanding of non-predictability well beyond traditional idioms such as kick the bucket: the term "subliminal idiom", coined by Sinclair (2004b, p. 22) conveys the subtle nature of the non-predictability that many of these expressions involve. The work asked how the strategic uses of traditional idioms observed by Strässler (1982) and Drew
and Holt (1988; 1998) in conversational exchanges extended to the range of expressions now recognised in contemporary phraseology and corpus linguistics. Rather than looking at usage in conversational contexts, however (as both Strässler and Drew and Holt did), the present work looked at written texts, where words on the page are the only resources available to meet writers' wants, needs and expectations.