On that bright morn of our primal dawn, we fried our wings on the shore.
Soaring from reed and marsh, we copulated and died.
The Angles then the Saxons came. The forests fell but the marsh lived on.
Till dark Bazalgette brought a river of shit, and the cold black rock was burnt for gas.
We all died then.
Now let the marsh revive.
Bring back our butterflies.
Meta morphosis from Father Thames.
Glory was and glory will.
The above examples illustrate the point that design sequences can begin at different points and proceed by different routes. Sometimes, the patterns of the existing site will be the most powerful influence on the final design. Sometimes, the nature of the intended human use will come first. Sometimes, an artistic conception will take priority. There is no One Right Way.