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The Scottish Electoral System

Additional Member System

The system used to elect members of the Scottish Parliament is the Additional Member System (AMS), this is a form of proportional representation which aims to allocate seats roughly in proportion to the votes cast. It is not perfectly proportional however it has the advantage of keeping the tie between a constituency and an MSP. The voter has two votes, the first vote is for a constituency MSP and the second for a party, these second votes will be used to decide how many MSPs from each party are required to make the result more proportional.

The first vote elects the constituency MSP in the same way as first past the post Westminster constituencies. Then the second vote is used to allocate MSPs according to the D’Hondt method. This technique divides the total list votes cast for a party by the number of (MSPs elected + 1) and continues until all list MSPs are allocated. An example based on the 2016 election result is provided later.

The Scottish Parliament Elections

The Scottish Parliament has 129 MSPs, this consists of 73 constituency MSPs and 56 top-up MSPs based upon the list vote These top-up MSPs are usually referred to as List MSPs, deriving their name from the ‘list’ that the political parties produce. The Party List ranks potential MSPs in order and if the party gains enough votes to merit an MSP then the MSPs are allocated in the order they appear on the List. If a List MSP resigns or dies, there is no by-election the next name on the List becomes the MSP. If there are no other names on the list then the place remains vacant until the next parliamentary election. One of the criticisms of the List system is that it does give power to the political parties as to who gets the higher places on the List, however, an individual can stand as a List of one, i.e. Margo MacDonald

Scotland is split into eight parliamentary areas each returning seven list MSPs:

  • Central Scotland
  • Glasgow
  • Highlands and Islands
  • Lothian
  • Mid-Scotland and Fife
  • North East Scotland
  • South Scotland
  • West Scotland


2016 North East Scotland Parliamentary Area Results

If we take the votes in the North East Region as an example, The North East Region includes:

  1. Aberdeen Central
  2. Aberdeen Donside
  3. Aberdeen South and North Kincardine
  4. Aberdeenshire East
  5. Aberdeenshire West
  6. Angus North and Mearns
  7. Angus South
  8. Banffshire and Buchan Coast
  9. Dundee City East
  10. Dundee City West

The North East Scotland result in May 2016 gave the SNP nine out of the ten constituency seats but no List seats. The List result was calculated as follows:








SNP / 1013,70838,79185,84818,44415,123Conservative
List Seat Calculations

In 2016, despite SNP winning 137,086 list votes the SNP gained no list MSPs.

ISP On The List

It should be noted that ISP will not stand in the constituencies and only intends to stand on the List. Its aim is to reduce the number of unionist List MSPs.

If the ISP party gained just 15% of the SNP list votes (7% of the total vote):

SNP / 1013,70838,79185,84818,44420,66215,123Conservative
List Seat Calculations, if ISP took 15% of SNP’s list votes

The result would be to replace a pro-union LibDem MSP (Mike Rumbles) with a pro-indy ISP MSP.

Insurance Against a Pro-Union Majority

An incredibly important factor to consider is what if the SNP do not do as well as expected in 2021?

What if the SNP focus on GRA reforms and the ‘Hate Crimes’ bill, give campaigning meat to the unionists and the SNP lack of movement on independence depresses the SNP vote?

Using the data from Gavin Barrie’s blog published here.

If the SNP lose 10 of their constituency seats and their regional vote share drops by 5%. The SNP do not actually pick up enough regional seats to compensate and the pro-independence majority is lost. This is because in the AMS system, for the constituencies splitting the vote loses seats, but for the list splitting the vote wins seats.

Instead of voting SNP on the list, those voters had voted ISP and ISP won just 20% of the SNP list votes (around 8% of the total vote), the pro-indy majority would be saved.

The most sobering aspect of all this analysis is that the AMS system used in the Parliament works very hard to not give ANY party a majority, by using a two-stage seat-assignment system with a heavy penalty to any party that’s “too popular” at constituency level and therefore is disproportionately favoured by FPTP.

The multiplicity of Unionist parties versus a single major pro-independence party actually gives Unionism a serious advantage in how regional votes are assigned, by applying fewer/smaller divisors to their vote.Astrong second pro-independence party balancing that out could be thedifference between holding onto Holyrood’s pro-independence majority or not.


  • ISP would have to reach critical mass – around 15% of SNP list votes which is 7% of the Total vote
  • There is no guarantee that the SNP will win a majority or every constituency seat. The list votes are an insurance policy where hopefully a constituency loss can be compensated by a list MSP. However, this would at worst just replace a SNP list MSP with an ISP list MSP so the pro-indy majority remains intact.
  • ISP are potentially a better partner than the Greens although the party will not support GRA reform and are likely to push for a more radical approach to independence.
  • A tactical message is difficult to deliver but it’s more effective at delivering a pro-independence majority for the Scottish Parliament. So, messaging and support in the MSM is crucial.
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