GSK plc, formerly Glaxosmithkline plc, has begun a significant new chapter in its history with the spin-off this week of its consumer business known as Haleon plc. While the high-profile new listing of Weybridge, Surrey-based Haleon (LON:HLN), the largest in Europe in a decade, grabbed the headlines, investors are keeping a sharp eye on GSK now that it is free to focus on developing and marketing novel drugs.