Jonty, you're getting way out of your depth now. If there are no written procedures for such eventualities, controllers cannot just go ahead and basically make them up as they go. Just imagine the legal implications, not to mention the public outcry, if something went pear shape which resulted in a mid air right over the city of Birmingham (seeing as 15 was in use apparently)! If the system is out and no procedural back-up exists, diversion is the only safe and legal option.