Quantum entanglement, the inseparable entwinement of particles at the atomic scale, has emerged from the realms of theoretical debate and now has the potential to revolutionize many areas of science and technology. Entanglement-based technologies are truly disruptive: they rely on the quantum nature of matter to perform functions which are intrinsically inaccessible to technologies based on macroscopic devices ruled by the laws of classical physics. The use of entanglement in systems relevant to NPL, where there is already a technical capability such as for atomic particles, photons and superconducting qubit devices, is reviewed. Gains in precision metrology are assessed and recommendations made on where entanglement may benefit current and future projects in the NMS Quantum Metrology Programme.