In this study Jonathan Stammers investigates code-switching in the new 40 hour, half million word "Siarad" corpus of informal spoken Welsh-English he helped collect. The key research question is whether or not there is an absolute or categorical distinction between code-switching and borrowing. English verbs are incorporated into Welsh by means of a highly productive routine involving the Welsh verbaliser suffix "–(i)o". For researchers such as Poplack, this would be sufficient to count the entire class as borrowings, but their integration is investigated further, largely because other researchers, such as Myers-Scotton would disagree with this interpretation. Analysis of the occurrence of soft mutation on the verb compares native Welsh verbs with two groups of English- origin verbs throughout the corpus, defined according to a dictionary criterion, but is also complicated by effects of overall word frequency of verbs. The study problematises the "distinct phenomena" approach to the code-switching/borrowing issue.