There are now nine 'Key Design Principles' for cycle infrastructure - defined by @transportgovuk.
Here's the first one:
"Cyclists must be separated from volume traffic, both at junctions, and on the stretches of road between them."

Here's the second of @transportgovuk's Key Design Principles for cycling infrastructure:
"Cyclists must be separated from pedestrians".

Number three on @transportgovuk's Key Design Principles:
"Cyclists must be treated as vehicles, not pedestrians."

Another of @transportgovuk's Key Design Principles for cycle infrastructure:

"Routes must join together; isolated stretches of good provision are of little value."

Another of @transportgovuk's Key Design Principles:
"Routes should only be designed by those who have experienced the road on a cycle."

The next @transportgovuk Key Design Principle:

"Routes must feel direct, logical and be intuitively understandable by all road users."

And other Key Design Principle from @transportgovuk:

"Routes and schemes must take account of how users actually behave."

Next up in @transportgovuk's 'Key Design Principles' is a very important one:

"Purely cosmetic alterations should avoided."

What does this mean? Beware mere paint. White lines can help bring clarity for cycle infrastructure, but you can't create safer streets with paint alone.