Apologies all - and thanks for the SMS Mono - Google are withdrawing the particular technology stack that the map has been running on, and the migration path they're proposing has been typically Googlish - fine if everything works, Fraggle Rock if it doesn't.
The various maps have been migrated to a new URL, I'll look into why the redirection from the old URL isn't working as advertised over the weekend.
In the meantime, the new URL for the EGXX map is here:
UK 48-Hour Notams : Warnings and Restrictions