When the first venues at the Riverside development in Canterbury opened two years ago, it was hoped this could mark the start of a new era for the city’s entertainment offering. With newly built flats for 500 students just yards away and another 189 affordable houses nearby, you would hope the leisure complex – built at a cost of £23 million to the taxpayer – would now be bustling. But when I visited on a mild Friday evening during Freshers Week, I was disappointed by how empty it was. Boom Battle Bar, possibly the main attraction now, wasn’t packed – though they did actually have people laugh…