World-wide wind energy capacity continues to grow with 1870 TW h in 2021, with annual additions of 113 GW in 2020 and 59 GW in 2019 with over 90% of the growth as a result of offshore wind farm installations. To attain 2050 net zero targets annual capacity additions of 250 GW are expected. Wind turbine assets require regular inspection and maintenance to ensure performance, compliance to standards and insurance requirements. A range of approaches are used in inspection and maintenance including airborne and platform mounted technologies, robots, as well as accessing the blades directly with rope assisted technicians. In addition to reviewing the merits and challenges associated with a range of approaches to offshore horizontal axis wind turbine maintenance this paper describes the design, trialling and in-service operation of a hexapod robot, along with options for its deployment. The robot is capable of deploying a wide range of measuring equipment and maintenance tools. The hexapod gait employed enables the chassis to be an end-effector, avoiding the use of traditional robot arms and the multiple degrees of freedom associated with the robot legs enable the robot to walk on both convex and concave surfaces as well as straddle a leading-edge profile on a wind turbine aerofoil. The robots have demonstrated functionality through multiple blade walks and tasks such as lightning protection system verification, inspections and blade surface treatments. The robot has the capability to work independently or alongside rope-assisted technicians.