You can achieve that themesandco behavior adding this to your child theme functions.php:
add_filter('tc_tagline_display', 'display_image_tagline');
function display_image_tagline($html){
global $wp_current_filter;
$class = "container outside ";
if ( in_array('__navbar', $wp_current_filter) )
$class = "span7 ";
// replace tagline
return '<div class="'.$class.'tagline-image site-description"><img src="https://apsdemo.intellect.uk.com/wp-content/uploads/2014/05/safe-image.jpg" alt="Just in case" title="We are gas safe" height="20px" width="50px"/></div>';
}
And this to your child-theme style.css, or your custom css:
.navbar .site-description{
float: right;
text-align: right;
}
.navbar.resp .site-description{
display: none;
}