Peatlands are valuable terrestrial archives of past climatic change, recording past variations in local (mire) hydrology and vegetation, alongside evidence for regional landscape change. The decadal to centennial resolution of peat cores makes the climatic and environmental signals that they contain of relevance to understanding human/environment interactions. Records of ombrotrophic mires are of particular value, as the depth of the water table reflects the balance between precipitation and evaporation (effective precipitation), and is thus closely linked to the regional climate. A variety of proxies have been applied to peats that record either the biological or redox response to changing mire conditions, including macrofossils, testate amoebae, and changes to bulk geochemistry. The last of these reflects the different decomposition processes that affect organic matter in response to the presence or absence of oxygen in the upper layers of the peat, which is driven by varying water table depth. However, bulk geochemistry of peat is also affected by the dominant plant inputs to the peat profile, which can also evolve through time and limit the isolation of a hydrological signal. Here, we show some promising new organic geochemistry proxies that can be applied to peats to understand both changing hydrology and the biogeochemical impacts that result. For example, the biomarker archaeol is argued to reflect methanogen activity below the water table. We also exploit the degradation of plant sterols under oxic conditions to identify times when the water table was low. In exploring a suite of mires, distributed from Ireland to Finland, we compare the environmental controls on these proxies. Furthermore, we apply this knowledge to examine the regional European expression of a key event in the late Holocene, the Sub-boreal / Sub-atlantic transition at 2.8 ka.