One issue we always have with the T3 framework is that for some reason with sh404SEF enabled to deliver a 404 page whenever this page is displayed the theme we have chosen for the site within the T3 template isn't being applied.

So I created a new theme and layout as detailed in the documentation and have assigned that as the default template style and this is applied to all pages however no matter what I do the 404 page won't inherit this and is displayed using the default layout instead - for example I removed the entire copyright section from our layout (by taking a copy of footer.php and renaming it custom_footer.php and then referencing this in our layout file) and so this doesn't appear on any pages however it does on the 404 page which indicates it is loading the default layout, not our custom one.

I've checked the ItemID of 404 page amongst other things but just can't get this page to display using the custom layout we have.

Any ideas?