Codeigniter: download file and redirect
Do it the other way around - redirect to the 'thank you' page and immediately redirect to the 'force download' page. This will start the download but leave the user on the 'thank you' page.
UPDATE:Try changing
<?php redirect('download/thassos_wonder_brochure'); ?>to
<?php redirect('download/thassos_wonder_brochure', 'refresh'); ?>instead.