The Central England Temperature (CET) record, starting in 1659 and maintained by the UK Met Office, is the longest unbroken temperature record in the world. Temperature data is averaged for a number of weather stations regarded as being representative of Central England rather than measuring temperature at one arbitrary geographical point identified as the centre of England.
A Scottish Chemist, Wilson Flood, has collected and analysed the 351 year CET record. Here is the comparison of the 18th Century with the 20th Century:
Wilson Flood comments:
“Summers in the second half of the 20th century were warmer than those in the first half and it could be argued that this was a global warming signal. However, the average CET summer temperature in the 18th century was 15.46 degC while that for the 20th century was 15.35 degC. Far from being warmer due to assumed global warming, comparison of actual temperature data shows that UK summers in the 20th century were cooler than those of two centuries previously.”