Hah!  Reader, I took that detour (from the north).   The bit round the Beckton Radar Mast is closed off.  But the bit over the lock-gate at Lockside Way has a fence that's easy to squeeze past  - then you can get all the way round "Albert Island" to find that King George V lock is lying on the bank in bits.   We had to trek all the way back to Upper Dock Walk.   But we did the whole Capital Ring in 4 days, and that was the only significant problem.
