The Prime Minister said during the election campaign that the 2015 election would be the last to use the first past the post system. Many systems have been put forward, including mixed member proportional, closed list, open list and STV, or single transferable vote.
One advantage of the current system is that it's very simple to understand. A five-year-old could navigate it easily. But some people fear that a system like STV is essentially a mathematical calculations affair. We can even imagine that people would meet in an isolated room, do mathematical calculations and decide the outcome of elections.
Why did your citizens assembly decide that this wasn't a problem?