The term refers to a particular style of gabled townhouse, common in Dublin from the late seventeenth century onward, characterised by a stepped or curvilinear gable facing the street rather than the more familiar plain parapet. The form arrived in Ireland with the influx of Dutch and Flemish craftsmen and influences that followed William of Orange's campaigns, and for a time these houses were a defining feature of the city's streetscape. Most were demolished or altered beyond recognition during the eighteenth and nineteenth centuries, which is precisely what makes any surviving example, or even a probable one, worth paying attention to.

The attribution here comes from Georgina Scally, who identified a Dutch Billy on Exchange Street Lower, though the date of the building remains uncertain. That uncertainty is itself telling. Dutch Billies tend to survive in altered states, their gables sometimes obscured by later render, raised parapets, or unsympathetic renovation, meaning that the street-facing silhouette which would once have announced the building's character is no longer immediately legible. Exchange Street Lower sits within what was once the dense commercial and civic fabric of medieval and early modern Dublin, close to the old city walls and the area around Wood Quay, and a vernacular merchant's house of this type would not be out of place in such a setting, even if its precise origins resist easy dating.

For anyone walking the area, Exchange Street Lower is a short street and easily covered on foot as part of a broader look at the surviving fabric around Dublin Castle and the Liberties. Because the building's date is unconfirmed and its Dutch Billy features may not be immediately visible from the pavement, it rewards slow looking rather than a quick glance. Check the roofline and the upper storey of buildings for any trace of a gabled profile stepping up toward the ridge. This is not a site with a plaque or a formal designation, so the interest lies in the act of looking carefully at a streetscape that has accumulated centuries of change, and in knowing what a particular roofline might once have signalled about the person who built it.