Dong, X., Bennion, H., Battarbee, R.W. and Sayer, C.D. 2011. A multiproxy palaeolimnological study of climate and nutrient impacts on Esthwaite Water, England over the past 1200 years. The Holocene 22: 107-118.
Quoting the researchers who did the work, "the response of diatom assemblages to changes in climate and nutrients over a 1200 year timescale was investigated by means of a multiproxy sediment core study involving radiometric dating, diatoms, grain size, loss on ignition and geochemical analysis," which was conducted on "Esthwaite Water," a small lake located in the Windermere catchment of the English Lake District at 54°21.56'N, 2°59.15'W. This work revealed four distinct climatic eras, which they describe as (1) Prelude to the 'Medieval Warm Period' (~AD 780-880), (2) 'Medieval Warm Period' (~AD 880-1350), (3) 'Little Ice Age' (~AD 1350-1880), and (4) Modern land use and recent climatic warming: ~1880-present.