This dataset provides daily aggregations of 3 cycling variables of base-load power stations in the GB power system for the period 2009--2017. It describes the number of startups, severe ramping events and average load factor of base-load generators (coal and gas-fired power stations with capacity > 100MW). It is the first of its kind, and may help improve our understanding of how cycling interacts with other factors in the power system such as renewables generation. The cycling data has been derived from operational data for the GB power system from Elexon's P114 dataset. We also include data on IRES (intermittent renewable energy sources; wind + solar) generation, total generation, and the number of active base-load generators in that year. Definitions of variables: - metered_wind_MWh: total generation of wind generators in the Elexon dataset. - unmetered_wind_MWh: estimates for total generation of unmetered wind generators from National Grid Demand data. - solar_MWh: estimates for total PV generation from National Grid Demand data. - total_IRES_generation: sum of metered_wind_MWh, unmetered_wind_MWh, solar_MWh (in MWh) - total_generation_MWh: calculated as the sum of all metered generation (from Elexon data), interconnection imports, unmetered wind generation and solar generation. - IRES_penetration: calculated as total_IRES_generation/total_generation_MWh - annual_active_baseload_gens: the number of base-load generators* which started up at least once in that calendar year. - startups_baseload: count of base-load *startups (count of events where production changed from < 1 MWh to >= 1 MWh) - load_factor_baseload: average instantenous output of base-load* generators divided by capacity during online hours only (hence measuring part-loading during operational hours) - severe_ramping_events: defined as a change in production of >= 25% of a base-load generator's capacity in consecutive settlement periods. * base-load generators defined as coal- and gas-fired generators of at least 100 MW capacity.