Alan commutes into London where he works as a concierge. In his spare time he composes songs with political themes.

But his beliefs also fuel a much uglier hobby: leaving nasty messages online – often hateful, racist and threatening.

One of those at the receiving end of his abuse is a high-profile political activist and businesswoman. Gina Miller gets so much abuse from people like Alan that she travels everywhere with security.

At our request, they have agreed to meet. What happens next might surprise you.

Presenter: Reha Kansara

(Photo Caption: A troll in the shadows / Photo Credit: Getty images)