Use of was with the pronoun you (as opposed to the standard form were) has been documented throughout England. Based on most recent work, it appears to be receding from the South, where it was once widely attested (Britain 2002: 20).
This construction is favoured in the North of England, where 73% of respondents either use this form or have heard it used locally; a comparable figure is also found in the Midlands (72%). The proportion of speakers who hear/use this form in other dialect regions is much lower (53% in Wales, 49% in the South, 24% in Northern Ireland, and just 9% in Scotland).