What about this:
http://myServer.com/cgi-bin/mapserv?&map=/home/harry/Mapfiles/MyMap.map&mode=itemnquery&qlayer=City-Database&qitem=name&qstring=('name'='London')
What about this:
http://myServer.com/cgi-bin/mapserv?&map=/home/harry/Mapfiles/MyMap.map&mode=itemnquery&qlayer=City-Database&qitem=name&qstring=('name'='London')