Colloquialisation is a linguistic process that describes how written discourse increasingly adopts features of casual conversation, thus "narrowing the gap between the norms of speech and writing" (Mair 1997). Originally, this process was understood as the spread of "informal" forms into standard writing, such as newspapers  (for example, it’s instead of it is in headlines; Mair 1997: 200). These choices reflected both stylistic trends and wider social shifts towards informality.

However, treating colloquialisation only as “writing catching up with speech” raises a key question: do these informal linguistic devices remain stable in speech or is speech also changing? If so, how do informality and orality interact (Koch & Oesterreicher 2012)? If speech itself evolves, then both speech and writing may be participating in broader stylistic change.

Abalo-Dieste and Pérez-Guerra (2021) examine two syntactic constructions, namely passive clauses and relative clauses, as markers of colloquialisation also in spoken British English. Using data from the spoken British National Corpus (BNC), we ask whether trends observed in writing (Leech et al. 2009; Baker 2017: 175) also appear in speech over time.