Golds, and resolute dominance, are becoming Laura Muir’s stock in trade. Records too, of which she now holds a decent clutch. History, genuine inscriptions in the pantheon of track and field, are rare and maddeningly difficult to obtain. Yet last night in Glasgow, inside the building where she frequently trains, the Scot became the first athlete in the half-century’s existence of the European Indoor Championships to acquire a pair of titles at successive editions. An unprecedented double-double. New ground indeed.