Tabbing through main navigation

The tabbing through the main navigation on the site does not go through in the expected order. Currently, when you tab from About it goes straight onto Sign Out. 

The expectation is that when you tab from About it follows the following order;

About -> What Do I Need To Do -> What's Changing? -> What Is Open Access
In terms of consistency, the OAE commenting rules and style should be applied throughout the codebase;
```
/**
 * Define Nav's methods (don't mention the p word)
 *
 * @param  {Object[]}   [dest]      An optional array to append the descendants to
 * @return {Object[]}               An array containing this Nav, child Navs, their children etc
 */
```