“Optical clocks with 1 × 10-18 uncertainty” was a three-year collaborative project (2016 – 2019). World-leading developments from this project in laser frequency stabilisation, atom trapping and interrogation techniques brought about improvements in both the accuracy and stability of optical atomic clocks across Europe. Further details can be seen from our publications as well as: Publishable Summary, (7 pages), April 2019 Longer Publishable Report, (25 pages), April 2019 Guidelines for developing optical clocks, which is a detailed technical resource (130 pages) Tutorial lectures and photos from the School on Optical Clocks, September 2018 For more information, please contact the project coordinator, Dr Rachel Godun at NPL.