I walked past the back of the Travellers Club yesterday and admired, as I often do, the rhythm of the three round-arched windows of its library looking out to its private garden.   It was designed by Charles Barry in the late 1820s and established the Italian palazzo style as the model for schools, banks and warehouses all over England.   But few later designs, including Barry’s later Reform Club next door, are as suave and sophisticated as the Travellers Club’s behind:-