The boxes shaded green show where children with the surname Cleasby had a forename in the top 10 most popular names for that year. So in 1924 Cleasbys followed the trend with John being the most popular name and in 1974 with Sarah.
The third table shows the top 10 boys and girls taken from BMD UK between 1837 and 1988.
No particularly surprising names favoured by Cleasbys.