What was done
The authors note that "under all realistic scenarios of future climate change, the frequency of heat waves in the UK is projected to increase significantly over coming decades, raising the question of how best to meet the public health threats that more frequent and prolonged periods of hot weather will present."  Hence, they provide data on patterns of temperature-related hospital admissions and deaths in Greater London during the mid 1990s to help shed some light on the subject.

What was learned
For the three-year period 1994-1996, cardiovascular-related deaths were approximately 50% greater during the coldest part of the winter than during the peak warmth of summer, while respiratory-related deaths were nearly 150% greater in the depth of winter cold than at the height of summer warmth.  Also, with respect to the heat waves that climate alarmists portray as being such ferocious killers, it is revealing to note that the mortality impact of the heat wave of 29 July to 3 August 1995 (which Kovats et al. find to have boosted daily mortality by just over 10%) was so tiny that it could not be discerned amongst the random scatter of the authors' plots of three-year-average daily deaths from cardiovascular and respiratory problems versus day of year.

What it means
Simply put, cold kills; and it kills far more people nearly everywhere every year than does heat ... and Greater London is no exception.  Consequently, global warming, which is expressed most strongly in minimum temperatures during winter, would do the people of Greater London much good.