For decades, political campaigners have feared just three things: big dogs, blisters and bad weather.
But with the explosion of video doorbell usage over the last few years, a new hi-tech threat has emerged for those pounding the pavements in pursuit of votes.
Campaigners knocking on doors ahead of the British general election on July 4 have learned to watch their Ps and Qs, even before they come face to face with potential voters.