UK temperatures essentially show no obvious warming for July over the last 365 years. There has however been a small warming effect in January since 1970, which may just be related to rapid population growth.
The Central England Temperature (CET) measurements is the longest continuous dataset in the world and covers a 360 year period from 1658 to 2016. Weather stations are concentrated within a roughly triangular area ranging from Lancashire, Bristol and London. The results are usually presented as annual temperature ‘anomalies’ relative to a 30-year seasonal average as for example by Ed Hawkins. However we can also simply plot the average measured temperatures for each month to identify trends. The resultant figure, as shown above, demonstrates that for CET there is no obvious trend in July temperatures at all. Perhaps after 1980 July temperatures have been slightly warmer than the long term 10y average, but well within annual variability. For the average temperatures in January the year to year variability is much larger still. Extreme cold winters occur throughout the CET record. In my lifetime I remember 1963(average -2C), 1979 (-0.5C) and 2010(+1C) standing out as being particularly cold, while the record coldest January is held by 1795 (-3C). The 10 yearly January average shows two recent warm periods lasting firstly from 1890 to 1940 and secondly from 1970 to 2016.
Is there really any evidence for anthropogenic global warming in CET? I think you would be hard pushed on the basis of this data to claim that CO2 alone is responsible for recent trends. If the second increase in 1970 to 2016 UK winter temperatures does indeed have an anthropogenic cause, then it is just as likely caused by rapid population growth as it is by CO2. Today some 50 million people in England warm their homes every January driving ~30 million vehicles on well lit roads in warm cities. That massive population growth has also mostly been concentrated within the CET triangle.