Jenny Reeves (@Jennyflyer1) was one of the first to post a picture on Twitter.
And Transport for London sounded the all-clear after the "invasion" had been averted.
The filming of Doctor Who has finished at Westminster Bridge, the Daleks are in the process of being removed.
More top news
A boy has died after he and his friends were attacked while cycling in north London.
Three police officers have been praised for their actions in helping a four-year-old boy who had become stuck on a roof in Newham.
A mother who lost precious photos of her dead infant son when her tablet was stolen is appealing for them to be returned.