 From there, its waters flow, via the Trent, to the Humber Estuary and the North Sea.At the eastern end, it is known as Aston Brook, giving its name to Aston Brook Street.It previously marked the boundary between Birmingham (then Warwickshire) and Smethwick (then Staffordshire); between the then Staffordshire country villages of Handsworth and Smethwick; and between Birmingham and Aston, before the city absorbed the latter district.