code order, you have the redirect after the doctype:
<!doctype html>
<html>
<?php
@session_start;
if ($_SESSION['UserID'] = 6) {
header("Location: http://www.domain.co.uk/product_contents_results.php"); /* Redirect browser */
} else {
header("Location: http://www.domain.co.uk/news_results.php"); /* Redirect browser */
} ?>
the redirect should be the first code block:
<?php
@session_start;
if ($_SESSION['UserID'] = 6) {
header("Location: http://www.domain.co.uk/product_contents_results.php"); /* Redirect browser */
} else {
header("Location: http://www.domain.co.uk/news_results.php"); /* Redirect browser */
} ?><!doctype html>
<html>