I think -ley is Old English, but it might be Old Norse as well. At least, it's also fairly common in southern England.cheltenham, egham, faversham. round here we have -thwaites and -leys which i think are norse.
-thwaite is Old West Norse (i.e. Norwegian), so it's more common in the northwest and around the Scottish coast and islands, whereas -by and -thorp(e) are Old East Norse (i.e. Danish), so you get them more in Yorkshire, Lincolnshire and East Anglia.