We have just had a seminar on the future development of Mayfair, run by Peter Murray, the chairman of New London Architecture.   Much of what is happening is potentially exciting:  the conversion of the old US Embassy building into a hotel and the renovation of Grosvenor Square;  the reduction in traffic roaring down Bond Street and the widening of pavements;  the creation of a new arcade of art galleries connecting Cork Street to Old Burlington Street;  a David Adjaye scheme immediately opposite the Ritz.   The question is how to maintain the existing layering of different uses, including art, culture, hotels, shopping and – I was reminded – clubs.   How to pay for the public realm developments which are needed when public funding is being cut.  And what role will the new Mayor play in all of this.