I did this walk twice, once as leader, once as relegate.
Finsbury Park stations > through the back (north) to Tollington Park. The map doesn’t show it but there’s a satisfying spiral curve past the Islington Arts & Media Centre through a park > then you can cut through some modernist council housing, past the fantastic murals at Duncombe School (http://gailastbury.com/playgroundwalls/duncombe.html) and on Sussex Bridge, then across to the roundabout below Archway. The modernist style of housing is repeated, albeit more upmarketedly on the other side of Whittington Hospital (named after the Lord Mayor of London), and the route climbs into Waterlow Park, again not representable on Bing Maps, and back down between the fields of Highgate Cemetery.
Through the mock-Tudor tenements of the Highgate private estate > tramp across Hampstead Heath, by the ponds that feed the Fleet.
Down into Hampstead village, and on to Finchley Road.
Curve round Belsize Road to Kilburn. Cut through to West Kilburn. Finish off at Paddington Recreation Centre, a park.