Just to add to @doubleodavey's suggestion, if you get off the DLR at Westferry, not only does this give you easy access to Poplar/20.5 miles, you can also walk the other way to about the 15 mile point. So you get to see people twice, and get to appreciate just how badly five miles round the Isle of Dogs has affected them!
If you're feeling particularly mobile you could start at Creek Road, Deptford (7 miles), then jump on the DLR at Greenwich to head to the Docklands. But avoid Greenwich itself, which is heaving. As is the Embankment.
Just to add to @doubleodavey's suggestion, if you get off the DLR at Westferry, not only does this give you easy access to Poplar/20.5 miles, you can also walk the other way to about the 15 mile point. So you get to see people twice, and get to appreciate just how badly five miles round the Isle of Dogs has affected them!
If you're feeling particularly mobile you could start at Creek Road, Deptford (7 miles), then jump on the DLR at Greenwich to head to the Docklands. But avoid Greenwich itself, which is heaving. As is the Embankment.