This is the recommended method for makeUrl(), though doing it in .htaccess will be faster and more efficient:
$url = $modx->makeUrl(54, "", "", "full"); // the new page ID goes in here
$modx->sendRedirect($url);
I'd ended up using the .htaccess method a few days since, already use is for non www. to www domain, just wanted to make the redirector method work though as it may come in useful in the future.
Thanks for the replies, will attempt research and understand regex syntax and structure.
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I'm currently lamenting over my decision to migrate to a .com from a .co.uk, even though 301 in place and webmaster tools has been notified of domain move. Definite drop in SERP. :'(