First-Past-the-Post is farcically vulnerable.
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1st, in FPTP a plurality of votes is enough.
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2nd, FPTP is ridiculously vulnerable to vote-suppression-by-sofa:  by suppressing registration, or by suppressing votes on voting day.

3rd, FPTP is particularly vulnerable because most voters perceive the result in their district to be non- competitive: it is easy to rationalise not voting.  Many districts would be competitive if people would get off the sofa.  The perception feeds latent apathy = fertile ground for vote suppression.
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4th, FPTP lets geography trump votes.  Analysis of Big Data permits micro-targetting to individual polls and houses based on web browsing habits and consumer spending habits.  Knowing what you buy, and what you read on the internet, almost always betrays how you will vote, too.

So, in a competitive riding they can identify which houses - which votes - are critical, and which messages, subliminal or otherwise, to send to those houses, computes, PDA's, phones.