Prediction of Caesium-137 (Cs-137) deposition from atmospheric nuclear weapons tests. The methodology uses a ratio of Cs-137 deposition and precipitation measured at Milford Haven by the Atomic Energy Authority extrapolated across Great Britain using a 5 by 5 km resolution UKCIP precipitation dataset. The prediction is for 31 December 1985. ; Methods ; The methodlogy used to estimate Cs137 deposition from atmospheric nuclear weapons tests was originally developed in the Artic Monitoring and Assessment Programme (AMAP) to estimate rates of radiocaesium transfer from soil to vegetation and food products. The method was then used to estimate Cs137 deposition from atmospheric nuclear weapons tests in Great Britain to allow quantification of Cs137 from the Chernobyl accident in 1986. Details of the methodology used can be found in Wright, S.M., Howard, B.J., Strand, P. Nylen, T & Sickel, M.A.K. 1999 Prediction of 137Cs deposition from atmospheric nuclear weapons tests within the Arctic. Environmental Pollution, 104, 131-143.