One dataset back to 1878 is the hottest each day got. This is the 'temperatures up to' figure weather forecasts give.
You can see 1976 was hot but also the trend over time. 1976 was very unusual for the 100 previous years. And now it looks fairly normal.
The English dataset goes back to 1659 for average daily temperatures. Here is how those temperatures have changed for June, July, August over that time.
June,July, August Central England average temperature since 1659
total dataset Mean: 15.3
1652-1700: 14.9
1701-1725: 15.2
1725-1750: 15.6
1751-1775: 15.3
1776-1800: 15.6
1801-1825: 15.1
1826-1850: 15.3
1851-1875: 15.3
1876-1900: 15.1
1901-1925: 14.9
1926-1950: 15.6
1951-1975: 15.3
1976-1994: 15:5
1994-2019: 16.0
1652-1700: 14.9
1701-1725: 15.2
1725-1750: 15.6
1751-1775: 15.3
1776-1800: 15.6
1801-1825: 15.1
1826-1850: 15.3
1851-1875: 15.3
1876-1900: 15.1
1901-1925: 14.9
1926-1950: 15.6
1951-1975: 15.3
1976-1994: 15:5
1994-2019: 16.0