It would be useful to have a word/short phrase to signify that the Conservatives won a greater share of the vote than any other party.
For a single electorate, that word is win.
You don't necessarily need another word:
Symbolic of the 'red wall' being broken in this election was seeing Blyth Valley falling to the Conservatives. Ian Levy won.
Or, if you are worried that people might not know who Ian Levy is:
Symbolic of the 'red wall' being broken in this election was seeing Blyth Valley falling to the Conservative candidate Ian Levy.
Another option is be explicit:
Symbolic of the 'red wall' being broken in this election was seeing Blyth Valley falling to the Conservatives. Ian Levy won with 42.7% of the vote.
Or, assuming your audience is somewhat familiar with the workings of British Elections:
Symbolic of the 'red wall' being broken in this election was seeing Blyth Valley falling to the Conservatives. Ian Levy, on 42.7%, was first past the post.
If, on the other hand you want to make clear the distinction between the vote in one electorate, as opposed to the overall vote, you could say
Symbolic of the 'red wall' being broken in this election was Blyth Valley, where the Conservative Ian Levy won with 42.7% of the vote.