london had grown , slowly , until , roughly a thousand years later , it met the tiny royal city of westminster immediately to the west , and , once london bridge had been built , london touched the town of southwark directly across the river ; and it continued to grow , fields and woods and marshland slowly vanishing beneath the flourishing town , and it continued to expand , encountering other little villages and hamlets as it grew , like whitechapel and dept-ford to the east , hammersmith and shepherd 's bush to the west , camden and islington in the north , battersea and lambeth across the thames to the south , absorbing all of them , just as a pool of mercury encounters and incorporates smaller beads of mercury , leaving only their names behind .