By Andy Silvester This time next week, London will be voting for its Mayor. It has not been a vintage campaign but perhaps the negativity apparent across the political spectrum may soon give way to some optimism about the capital’s prospects. A closely watched annual survey pegged London as, again, the best place to work. And indeed play. That “play” is vital to our competitiveness; the only people who genuinely feared that post-Brexit bankers would up sticks for Frankfurt had clearly never been to Frankfurt. One cannot dance and dine and drink like one can in London. But our hospitality indus…