Could that be because a lot of local authorities only elect a portion of their councillors at any given time? So what may have been 18 Conservative councils would always have been 18 Conservative councils because the number of seats up for grabs would not change the majority.
In Cornwall Independent/ Unattached councillors have the most seats following Thursdays elections.
Cornwall results were:
Independent 30.08% 37 +4
Liberal Democrat 29.27% 36 -2
Conservative 25.20% 31 -18
Labour 6.50% 8 +8
United Kingdom Independence Party 4.88% 6 +6
Mebyon Kernow 3.25% 4 +1
Green Party 0.81% 1 +1
1st column is % of vote, 2nd column number of councillors elected, 3rd column variance in number of councillors from previous election