London Fire Brigade has confirmed the alarm has been triggered, but there is no sign as yet of any fire.
For most people, a journey from London to Dover and back is a simple matter of getting in the car or on a train - and a couple of hours later, the journey's over. But this weekend seven lads from Kent are doing that trip, both ways - on scooters.
David Johns went to see them preparing for their epic journey and spoke to Nick Hardinges and Luka Syplywczak.
Hundreds of protesters gathered at Westminster today in support of a Gurkha who's been on hunger-strike for 13 days. Gyanraj Rai is demanding that 25,000 Gurkha veterans are given the same pension rights as their British comrades.
Meanwhile, a teenage boy from Kent has launched a Government e-petition in support of the hunger striker. John Ryall reports.