The London Plan tells us to optimise the use of land, and residential densities. It also tells us to conserve and make use of 'heritage assets'. This project in Banner Street (EC1) is a built case study of what happens when you try do both at once.
All very polite and neutral, to 'respect the character' of the old facade. (Depending on who did it, the architects may well have used the word 'palimpsest', inaccurately, in making the case for it.)
In Moscow, in new building projects as in other respects, they are a bit more gung ho:
Not exactly refined, but entirely in the spirit of modern Russia.
More homes are needed in London, and one way of providing them is to build on top of existing buildings a lot more than we do. As the above examples show, this doesn't need to be limited to the cautious set-back single extra floor, justified on the grounds that 'you'll never notice it'.
In Shoreditch, the Hackney planners are to be congratulated on being persuaded by Duggan Morris's interesting looking scheme (above - photo credit Jack Hobhouse), now on site, to add a further three storeys to a three storey building in Curtain Road. A two or three storey building in central London is not optimising the use of land.
Westminster City Council have woken up to the fact that many residential areas of the centre of London now resemble a ghost town out of office hours, with crazily expensive flats and houses, owned by people who live somewhere warmer, being treated as assets rather than homes. This is partly a result of the rationing of the supply of homes. We should be encouraging people to add a floor or a few floors to every building in London that could take them, rather than preventing them.