The variable phenomenon in which /t/ can be realized as a tap or rhotic approximant in varieties of Northern British English (commonly referred to as t-to-r , Wells 1982: 370) has received some attention in English linguistics as debates have appeared over how best to model the phonology of the phenomenon (e.g. Carr 1991, Docherty et al 1997, Broadbent 2008). The occurrence of t-to-r seems to be constrained by the preceding and following phonological environment in a largely systematic way and so it is often accounted for within a rule-based model of grammar. Problematically, however, the rule does not apply blindly across the board to all words which fit the specified phonological pattern. Instead, t-to-r shows evidence of being lexically restricted, and this fact has recently encouraged a usage-based interpretation. Until now, there has been relatively little attempt to test the usage-based thesis directly with fully quantified data gleaned from naturally occurring conversation. This paper investigates the extent to which certain usage-based predictions can account for variation attested in t-to-r in Liverpool English. Using oral history interviews with Liverpool English speakers born in the early 1900s, we examine the usage-based predictions first proposed by Broadbent (2008) that t-to-r is more likely in (a) high frequency words and (b) high frequency phrases. There is some support for the importance of lexical frequency as a motivating factor in the use of t-to-r but our data do not fully support either of these claims wholesale. We suggest that t-to-r is not constrained by simple token frequency or phrase frequency alone but by a combination of both. Finally, we explore the possibility of employing notions from Cognitive Grammar such as schema strength (e.g. Taylor 2002, Bybee 1995: 430) in our interpretation of these data.