The US Embassy in London, UK, has commented that visa services at that
location will be limited during July and August 2012 for all
nonimmigrant visa categories. This is due to the Olympics taking place
in London during that time. Applicants are encouraged to apply for visas
during the spring and early summer for a stronger possibility of an
appointment; availability of appointments cannot be guaranteed during
July and August. The Embassy has opened up its appointment calendar
through the end of June to facilitate this.
Please note that travelers who plan on entering the United States
without a visa under the Visa Waiver Program (by air or sea) who do not
have travel authorization approval under the Electronic System for
Travel Authorization are urged to register now to travel during the
summer. If registration is denied, these travelers will be required to
obtain visas.