The development of a certification infrastructure to support the widespread adoption and commercialisation of Quantum Key Distribution (QKD) technology has just begun. This is being led by the Industry Specification Group (ISG) of the European Telecommunications Standards Institute (ETSI) on QKD (ETSI ISG-QKD), and European NMIs play a prominent role in its work on measurement-related standards. The MIQC and MIQC2 projects developed methods for characterizing the quantum-layer components, namely the single-photon sources and detectors, of fibre and free-space QKD systems. These projects also devoted special attention to improving measurement traceability in the photon-counting regime, activities that started less than ten years ago with the IMERA+ qu-Candela project. An important result was that NMI members of the ETSI ISG-QKD were able to lead the drafting of Group Specification document (pre-standard) specifying procedures for characterizing the single-photon source and detector components of ‘GS QKD 011 QKD Quantum Key Distribution (QKD); Component characterization: characterizing optical components for QKD systems’, arguably the first measurement standard addressing a quantum technology. More recently, ‘GR QKD 003 Quantum Key Distribution (QKD); Components and Internal Interfaces’ was published, with significant input from the NMIs. It summarises the main QKD protocols and properties of the sources and detectors used in implementing such protocols. Of particular note are that new protocols (e.g. COW), free-running single-photon detectors (e.g. SNSPDs and free-running InGaAs SPADs) and continuous-variable QKD are emerging, and these new devices and protocols will also require metrology to support them in the near future (assuming they remain on their current trajectory towards commercial use).