CENTRAL ENGLAND AND GLOBAL TEMPERATURES
On our web site we have a range of climate reconstructions (http://www.climatedata.info/temperature/effects/index.html). One which stands out from the others is the one which was included in the IPCC 1990 Technical Report as Figure 7.1c. This figure is included in Chapter 7.
In the report it is clearly stated that the figures are to be taken as representing global temperature variations. It appears however that the third figure is based on the temperature record for Central England as developed by Lamb (1965). Subsequently a temperature record based on instrumental readings was developed by Gordon Manley (no relation) and others.
The following chart compares that record (downloaded as the file 'cetml1659on.dat') with global and hemisphere temperature estimates produced by the CRU.
As can be seen there is good agreement betwen the Central England temperature record (represent as a 5-year centred moving average), the Northern Hemisphere estimate and, even, the Global one. All the temperature estimates have wide errors bands so perhaps the 1990 figure is not such an outlier as it might appear.