From mrspencil: a walk in the woods
The woods near his current residence are not so drastically different from those of Hampstead Heath. Lille is warmer at this time of year than London, of course, but he just imagines that it is England's summertime rather than France's autumn and it is as though he is there. In London.
He has missed London. Its theatres, parks and, of course, his beloved flat. None of it can be recreated, but the woods are not so far off. If Watson were here, with his cane and moustache and conversation, the imperfect copy would be a touch closer to perfect. He walks these woods often, yearning for his life in London and conjuring the sound of Watson's familiar, uneven gait crunching through the fallen leaves.
Three years has been more than long enough for him to know with certainty where he truly belongs. In England, in London, with his dear friend at his side.