|Photo via @RicksterLondon|
In fact it's not entirely clear how they are there. There was some confusion as to whether that space was a designated car park (which it is not), and then as to whether they had the right licence. The police moved them on for a day, but then they were back with the right licence.
The councillors are trying to get to the bottom of it as there is even more confusion as to whether this is a Network Rail issue or a Camden council issue. The land is owned by Network Rail but trading licences should normally be given by the council. That's what happens when you privatise "public" space I'm afraid (if you'll allow me to ride one of my hobbyhorses for a moment).
I have a sneaking suspicion that Mr Whippy and his frankfurter friend won't be there much longer, so if you like a 99 Flake or a £3 hotdog, then get down there quick.