During my working life I covered the whole of the UK, and because this predated Sat Navs, or indeed mobile phones, needed to use maps, and after several years had covered so many miles that I rarely needed to use them very often, and quite frankly the monster London A to Z that covered the area encompassed by the M25 was highly impractical when on the move, as it was literally organised in horizontal slices that I often passed though diagonally requiring a heck of a lot of thumbing pages, thus I pretty much picked up the famous "knowledge" not only of the capital but the whole UK over the years