My dad was quite broad (as in dialect) and people often said I swapped tongue when talking to him. Working in Cheshire amongst the Knutsford set I often get pulled for my accent. In fact one manager actually said it was one of my strengths in that people mentioned to him that my accent came across as straight talking and people tended to believe what I said where they might not have done if it had been anyone else. Also dealing with a lot of southern people(an philipinos and Indians) in my job it is sometimes good to stick some dialect in the conversation just to confuse them a bit
I would say that I do find it easy to 'drop' teh accent when I need to though(i.e. when a big wig from down south joins a phone conference)
Ian