In his remarkable work _Les Récits de l'Infini_, the famous French astronomer, Camille Flammarion, hit upon a somewhat original device to bring vividly before his readers the fact that the heavenly bodies are seen by the dwellers upon earth, not as they are now, but as they were when the light revealing them left them countless ages ago. Having endowed an imaginary observer with immortality, he takes him from star to star, showing him all the kingdoms of the world at the various stages of their development, and finally makes him a witness of the Creation by the aid of the light that first shone upon the waters of chaos. Unfortunately, the student of history cannot hope to share the supernatural facilities of vision of Flammarion's hero, but for all that he can lay to heart some of the lessons of the astronomer's story by bringing to bear upon his task the sympathetic imagination which alone can enable him to reconstruct the past, and by remembering that that past should be judged not by the light of modern progress, but by such illumination as was available {2} when it was still the present. No matter what the subject of study, the accumulation of facts is of little worth without the power of realising their interdependence, and this is very specially the case with the complex theme of London, in which an infinite variety of conflicting elements are welded into an unwieldy and by no means homogeneous whole, for in spite of the obliteration of landmarks and the levelling influences of modern times, each of its component parts has a psychological atmosphere of its own. Illusive, intangible, often almost indefinable, that atmosphere affects everything that is seen in it, and is a factor that must be reckoned with, if a trustworthy picture of the past or present is to be called up. The truth of this is very forcibly illustrated in the outlying suburbs of London, with which the present volume deals, for though these suburbs now appear to the cursory observer to bear the relation of branches to a parent stem, many indications prove that they were all not so very long ago independent communities, which were gradually absorbed by their aggressive neighbour, whose appetite grew with what it fed upon, and is still unsatisfied. This is very notably the case with Hampstead, which less than a century ago was still a mere village, the history of which can be traced back for more than a thousand years, and which, through all its vicissitudes, may justly be said to have been true to itself, for its inhabitants have from first to last resisted with more or less success every attempt to merge its individuality in that of the metropolis. {3}