Dunning, D.J. Aden, P. Angal-Kalinin, D. Clarke, J.A. Collier, J.L. Fell, B.D. Green, J.S. Henderson, J. Marangos, J.P. Mathisen, S.L. Militsyn, B.L. Roper, M.D. Snedden, E.W. Thompson, N. Walsh, D.A. Williams, P.H. JACoW Publishing Geneva, Switzerland 2673-7035 978-3-95450-224-0 10.18429/JACoW-FLS2023-TU4P13 English 103-106 FEL photon laser electron free-electron-laser Contribution to a conference proceedings 2024 2024-01 https://doi.org/10.18429/JACoW-FLS2023-TU4P13 http://jacow.org/fls2023/papers/tu4p13.pdf In October 2022, the UK XFEL project entered a new phase to explore how best to deliver the advanced XFEL capabilities identified in the project’s Science Case. This phase includes developing a conceptual design for a unique new machine to fulfil the required capabilities and more. It also examines the possibility of investment opportunities at existing XFELs to deliver the same aims, and a comparison of the various options will be made. The desired next-generation capabilities include transform-limited operation across the entire X-ray range with pulse durations ranging from 100 as to 100 fs; evenly spaced high rep. rate pulses for enhanced data acquisition rates; optimised multi-colour FEL pulse delivery and a full array of synchronised sources (XUV-THz sources, electron beams and high power/high energy lasers). The project also incorporates sustainability as a key criteria. This contribution gives an overview of progress to date and future plans.