The design now poses another conundrum. The new steps rise to the terrace in front of the National Gallery, which in turn butts up against a blank stone wall. Because there was always a busy road here, the Nat Gall's original architect William Wilkins had no space to put a grand flight of steps up to his portico. So he put cramped little staircases on either side instead. The Gallery's present architects, Sir Jeremy Dixon and Ed Jones, propose putting this right with a new ziggurat of steps. That way, you would be able to walk in a straight line from the square below via the new terrace and up into the gallery without having to make a dog-leg. There is logic in this, but beware: if it is done, it will make the square seem even more elongated. It will become an axial cascade, so different from Barry's much subtler arrangement of 1845.

Looking at the Foster alterations makes you realize just how clever those Victorian and Edwardian architects were. Now he has thrown everything out of kilter, there is only one visual solution: move Nelson, the lions and the fountains north a few yards. I can't see it happening, can you?