A train, a tram, a bus and a short walk later, we arrived at the Ravensbourne Open Space. The rain began in earnest, and even the Keston Common ducks tucked their heads under their wings. The Ravensbourne Open Space had several paths that crisscrossed the river (or "ditch" as one might like to call it) to Keston village; after that we had to leave the river for the London Loop and some mild trespassing around the farms of Barnet Wood. There are two schools of thought on this; one can dress in camouflage, greasepaint and balaclavas and trust to silence, speed and stealth to hasten one's path through private land. Or you can hope that a goofy grin, foreign accent and a mycathatesyou.com t-shirt will reduce any confrontations to mere exasperation instead of GBH. My first glimpse of London (and a stoat) was at a trout fishery near Hayes - you can just make out Canary Wharf in the right side of this picture.
Once in Bromley, we saw less of the actual river, but the course was easier to follow on the roads. I saw an old stone mile marker outside #6 Hayes Road - I could make out the word "Bromley" but nothing else. Adam and I stopped for a nacho lunch at Chico's with moral_vacuum, ivory_goddess, realtan_dannan and thedarkpoint. They took us to see the Bromley Zoo, and we set off again through Church House Gardens, Shortlands Golf Course, and Beckenham Palace Park.
The now-culverted river was surprisingly scenic through Bellingham, Southend and Catford. Unfortunately, railway fences prevented us from seeing the confluence of the Ravensbourne with the Pool River, but I did enjoy the dire warning of the Southend Homebase to those who might pilfer their fish. We continued through the tranquility of Ladywell Fields to Lewisham; there is a lot of redevelopment around the river that isn't reflected on streetmap.co.uk, so we could follow the course easily and admire the new landscaping. Lewisham Council has also made a feature of the Ravensbourne confluence with the Quaggy River, even though you have to walk through the bus station to see it.
The wildlife in Brookmill Park were impressive in their variety, although my favourite part of the walk was at the Creekside Centre just after the Ravensbourne becomes the tidal Deptford Creek. Here the Ravensbourne really shines as a living urban river - from the Creekside Centre's bridge I could see industry, train and DLR lines, the Laban Dance Centre and boats, but around the mud flats I saw a nesting heron (or crane? I can't tell the differece) plus ducks, geese, coots, moorhens, gulls and even a few foxes.
We pressed on to the Thames and saw the green lit dome of the Greenwich foot tunnel just as it got dark. Although we'd vaguely intended to collapse in a Greenwich pub, we received a very kind invitation to dinner from haggisthesecond and naxos, so we trooped through the foot tunnel and could just make out the confluence of the Ravensbourne with the Thames from across the river before heading into the city in search of food and friends. Pictures from the walk are here. Edit - link fixed now.