Found an issue, if I click the 'Add New Redirect 'button I am getting a php error:
Looks like that is just a PHP notice because PW is in debug mode. But I did confirm there is an uninitialized var there. I think this may be my mistake. I have submitted a pull request to apeisa with a correction for this.
So normally I need to create a redirect from /about-us/ to /about-us/history/ is this correct?
I'm guessing that /about-us/ is already an active page on your site? Since you've already got a page living at that URL, that page is handling the request rather than the redirects module. To do that redirect, you'll want to edit that page's template and do the redirect from there, i.e.
<?php
$session->redirect("history/");
But that's not particularly reusable. I know on some sites, it is a common need to have a section page (like /about-us/) redirect to the first child page. If that's your need, you may just want to setup a new template called section-redirect (or something like that) and do this:
<?php
$session->redirect($page->child->url);
That way it's reusable for similar needs on any other section page.
Lastly, lets just say you wanted a generic "redirect" template that you could use on any page to redirect to any other URL. You'd want to create your template called "redirect" (example) and create a new field of type "URL", giving it a name like "redirect_href". Add your "redirect_href" field to your "redirect" template. Edit your "redirect" template to have code like this:
<?php
$session->redirect($page->redirect_href);
Then set the "about-us" page to use your "redirect" template. Edit it and type in the URL you want it to redirect too, like "/about-us/history/", in this case. Then you can continue to reuse that redirect template anywhere else that you might need an existing page to redirect elsewhere.
The value of the Redirects module is that it will handle redirects for pages that aren't in your site tree. But if the pages are already in your site tree, and you want them there, then you'd want to use one of the methods described above rather than the Redirects module.