I walked from Tate Britain to Tate Modern in London last week, looking in on a few exhibitions. The walk on the south bank of the river from Lambeth Bridge down to Bankside on a bright, crisp day was just great. The city landscape mixed with a moody sky and low Autumn sun made for an easy palette. St. Paul’s, the cluster of high-rise City buildings and the river’s bridges provided rich pickings, both from ground level and on high from the Tate Modern’s viewing platform.