There has been plenty of discussion about electorate “cup of tea” deals recently, in which a large party agrees to give a small party an easy run in an electorate, so that the small party is more-or-less guaranteed seats in Parliament when they might otherwise get kicked out. Vernon Small has more specunalysis about National’s suite of deals this morning.
Some of the concern is about
“overhang” “coat-tailing” (HT: @trevormallard) where a party on, say, 2.5% can gain three or even four seats off the back of a single electorate win. The impact of that on Parliament overall is clear.
But what of the deals with true minnow parties, like United Future or ACT? If a party is only polling enough to get one seat anyway, does it matter to Parliament overall whether the small party wins an electorate or its client big party wins it instead?
The answer is “possibly, yes,” because we can never be sure which party ultimately loses a seat to accommodate the new minnow party in a 120 seat parliament. Sometimes, it will be the big party making the deal, at which point everything comes out square. But other times it will be some other party that was entirely outside the deal. At that point the consequences can be huge.
Here’s an example that uses pretty plausible polling numbers, the Electoral Commission’s St Lague method for handing out list seats, and the Epsom deal as a test case:
No Epsom deal
By rights, the potential Centre-Left coalition should have more seats in Parliament than the current Centre-Right Coalition, because they won 1% more votes. And without an Epsom deal, that is what would happen.
But with the Epsom deal, ACT gets an electorate seat in place of National, and that is not all that changes. National’s overall entitlement in Parliament remains unchanged (it is based only on the St lague calculations), so it picks up an extra list seat to offset the electorate seat loss. That list seat comes at the expense of Labour in this case (again due to the St lague quotients), and all of a sudden the Centre-Left’s 1% vote advantage comes to nothing, and we have a 60-60 deadlock.
This situation occurs roughly half the time, meaning than an electorate deal with a minnow leads on average to a 0.5 seat advantage towards the Coalition making the deal.