It is democracy.
We dont elect the prime minister in this country.
We elect a local MP. That is all. The party with the most MPs becomes the leading party, and they choose their own leader. That party leader is our PM.
You may elect your local MP because of the party they are a member of or you may elect them because they, specifically, are the person you want as your local MP. It doesn't matter. Either way, you choose and MP, but you dont choose the prime minister.
Consverative are the leading party until the next GE. They choose their leader. That's who we get as PM.