We present a conceptual design for the UKIRT Planet Finder (UPF). It is a fibre-fed high resolving power (R ∼ 70,000 at 2.5 pixel sampling) cryogenic echelle spectrograph operating in the near infrared (0.95–1.8 μm) and is designed to provide 1 m/s radial velocity measurements. We identify the various error sources to overcome in order to achieve the required stability. We have constructed models simulating likely candidates and demonstrated the ability to recover exoplanetary radial-velocity (RV) signals in the infrared. UPF should achieve a total RV error of around 1 m/s on a typical M6V star. We use these results as an input to a simulated 5-year survey of nearby M stars, which has the sensitivity to detect of the order of 30 terrestrial mass planets in the habitable zone around those stars. UPF will thus test theoretical planet formation models, which predict an abundance of terrestrial-mass planets around low-mass stars enabling critical tests of planet-formation theories and allowing the identification of nearby planets with conditions potentially suitable for life.