This paper presents written diary and audio-recorded data from one early talking child acquiring British English. This child's production is typical in many ways, however, before mapping different auxiliary distributions onto different speech acts, this child seems to posit a default auxiliary-initial word order regardless of utterance purpose. It argues that this rule emerges as a result of Yang's (2012) Tolerance Principle, a Learning mechanism applied by the child to use frequencies in his input to hypothesise and test the productivity of (morpho)syntactic rules. Variational Learning (Yang 2002, 2004) then helps account for the emerging competition between different mapping rules (auxiliary-subject vs auxilliary-medial). The interplay of Variational Learning and Tolerance Principle proposed here paves the way for new research in word-order-mapping during the early stages of multiword combinations. Independent motivation for the importance of investigating the acquisition of word-order mappings comes from competition of grammars (Kroch 1989) in language change and the growing body of evidence for the richness and complexity of non-canonical data in the learner's input.