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You have a priority crossing, adjacent to the ped's Zebra, known as a Tiger crossing, which is a Zebra for cyclists. There's one just North of London Fields, here: https://goo.gl/maps/YJDqiFKb8uD2, they are very new/rare though.
The sketch is a preliminary drawing, a complete scheme was apparently ready to go, according to Gilligan, who would know I guess.
Here is one that has got the go ahead in CAmbridge: http://road.cc/content/news/211156-cambridge-get-its-first-true-dutch-roundabout
Backstop-
This roundabout can get mega congested in the evening and is super popular with cyclists. A priority straight on for cyclists would be insta grid lock at rush hour. (They should really be focusing on reducing central London motor traffic but that's a different debate).
Also, is this safer? It only takes one HGV to not understand the Tiger crossing and you've got another squishing.
Scrabble
But how does it help? Do you still have to cut across anyone turning left?