Appealing to the individual voter?
"...to map the fears and desires of swing voters, and design highly personalised messaging that would appeal to them."
Which basically summarises one of the (many) core problems of UK politics - the main parties are only interested in convincing each person to vote for them and put them in power. It doesn't matter if that means promising different random (and impossible) things to each voter, even if you know you can't deliver (£350 million...etc). Just tell them what they want to hear.
If we want to clean up politics (and I think most of us do) we need to get to a point where the candidates for election say what they believe in. What are their principles and philosophy? What is their vision for a future Little-Snodbury-in-the-Wold, Britain, Europe or the World? It's good to know as well what specific policies they would implement to move towards that vision, but policies should come from what the candidate believes in, not be something to get the vote of Mrs F Ashist round the corner.
The candidates task is then to persuade the voters to support their vision, not to promise them the impossible.
There are some smaller parties who do actually work that way. I'll leave the reader to decide which ones.