The Transport for London website now includes some excellent information on walking.
It includes a section some of our favourite routes around London with this map of the strategic routes.
The site also includes a Journey Planner that is defaulted to walking, and allows you to enter your speed, how to see some of London's best known sites on foot, walking steps and times between stations, how to find your way around London on foot using the Legible London signage, and a section on the benefits of walking.
In March 2017 TfL launched two extended versions of the Walking Tube map to help those travelling outside of central London. The maps include Zone 3 stations for the first time with estimated walking time and steps between stations. They now also include National Rail stations - giving people even more opportunity to easily save time on everyday journeys on foot.
Follow the link to the site here.