London's Olympic Ambassadors are back on the streets in a pilot project at St Pancras Station.
The volunteer force will offer advice to visitors on how to get to attractions, restaurants and shopping areas.
But, as Rags Martel reports, they started with something a bit more dramatic.
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The 24-year-old was unarmed and the incident is not being treated as terror-related.
Some platforms have been taken out of service with disruption expected to continue until the end of the day.
The Met Office has extended its weather warnings for snow and ice to cover vast swathes of the country, including London and the South East.