It’s the height of the silly season. Unseasonal heatwaves have swept Scotland. Beaches here on the Hebrides are packed. Scots have even been seen swimming. City streets are quiet. Summer sales are on. Politicians are abroad. Voters are focused on sunscreen, Playstation for the kids and time off in the sun. It’s hardly the time for a massive breakthrough in the independence campaign. Yet last week was a turning point – the week in which key narratives in the Better Together campaign began to crumble.