Tinder claims it makes 15m matches a day and it is about to launch a new, premium service, but while romance can flourish online, Tinder and Plenty of Fish, and other such services, are just as likely to be used for casual-sex hook-ups.

The family of a man they believe went on a shooting rampage near a university in Santa Barbara, California, called police several weeks ago after being alarmed by YouTube videos “regarding suicide and the killing of people”, a lawyer said today.