For a 14-metre extension lead with a 2.5mm or 4mm core at 240V, the most common options are heavy-duty industrial or "Arctic" grade leads, typically used for site work, caravans, or high-load power tools. The 2.5mm² cross-section is superior to standard 1.5mm² cables because it significantly reduces voltage drop and can safely handle higher currents. 

14MTR EXTENSION LEAD 110V 32AMP