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.