It is well known that in the Cockney dialect in former times, the letters V and W were interchanged. Thus William (and Dinah) became Villikens. Also in Dickens, we get 'werry' instead of 'very'. There are many old broadsides showing this feature, between 1806 and the 1860's - does anyone know the approximate date range in which these letters were interchanged and why? Was it German influence?