The colours of London are grey and brown — the grey of sky and river, the brown of the brick. The river gives London much of its character — wide enough to act as a formidable physical and psychological barrier, dividing South London from the rest, though not wide enough to separate the two Londons as decisively as the Mersey separates Liverpool from Birkenhead. But it is the bricks, brown sometimes with flashes of yellow, bricks found in every part of pre-1914 London, except for a white-stucco corner of the West End, that emphasise London’s role as capital not only of international capitalism and of the British Empire, but of south-east England. The brown bricks are as characteristic of and exclusive to London and its hinterland as bright red brick is distinctive of the West Midlands or white brick of the Eastern Counties. On the eve of the First World War, 50 per cent of those living in London and born elsewhere were short-distance migrants1, as against 25 per cent born in other parts of England, 9.9 per cent born in other parts of the British Isles and 15.1 per cent born abroad or in the colonies. In 1881, when the Irish-born proportion was higher, and the proportion of foreign immigrants substantially lower, 52.3 per cent of immigrants were short-distance as against 28.6 per cent from other parts of England.