The d'Hondt System
This is a voting system for allocating seats to parties using a party list system. It is designed to give small parties some representation while giving the majority of seats to the main contenders. It is the system used for EU elections, where the country is divided into a number of regions, each electing several MEPs. London elects 8 MEPs.
The Modified d'Hondt System
The d'Hondt system may be modified for use in elections where there are a number of constituency seats and a number of top-up seats from party lists. It is the system used for GLA elections, where there are 14 constituency seats (each consisting of either two or three neighbouring boroughs) and 11 top-up seats.
Both:
The full d'Hondt method may be considered to be a special case of the Modified version in which there are no constituency seats, so the explanations may be taken together. It works in the following curious fashion:
- Usually a threshold vote has to be reached to receive any seats (5% in both the EU and GLA elections)
- For the first seat allocation, each party's list vote is divided by (the number of constituency seats won + 1). The party with the largest vote after this process is allocated a seat.
- For each subsequent allocation each party's original list vote is divided by (total seats so far + 1). The party with the largest vote after this process is allocated a seat.
- This process continues until all seats have been allocated.
Here's an example, from the 2008 GLA election: In the constituencies the Conservatives won 8 seats, Labour 6 and nobody else won any.
There were 11 seats to allocate via the top-up lists and the voting percentages were (roughly):
Conservative 34.1%
Labour 27.1%
Lib Dem 11.2%
Green 8.3%
BNP 5.3%
(the total does not come to 100% because there were a number of other parties failing to reach the 5% threshold)
The allocation process then worked as follows:
O = Original vote share
S = Seats so far
V = Vote share counted for this allocation
| Voting | Con | Lab | L.D. | Green | BNP | Seat | ||||||||||
| Round | O | S | V | O | S | V | O | S | V | O | S | V | O | S | V | alloc to |
| 1 | 34.1 | 8 | 3.8 | 27.1 | 6 | 3.9 | 11.2 | 0 | 11.2 | 8.3 | 0 | 8.3 | 5.3 | 0 | 5.3 | L.D. |
| 2 | 34.1 | 8 | 3.8 | 27.1 | 6 | 3.9 | 11.2 | 1 | 5.6 | 8.3 | 0 | 8.3 | 5.3 | 0 | 5.3 | Green |
| 3 | 34.1 | 8 | 3.8 | 27.1 | 6 | 3.9 | 11.2 | 1 | 5.6 | 8.3 | 1 | 4.2 | 5.3 | 0 | 5.3 | L.D. |
| 4 | 34.1 | 8 | 3.8 | 27.1 | 6 | 3.9 | 11.2 | 2 | 3.7 | 8.3 | 1 | 4.2 | 5.3 | 0 | 5.3 | BNP |
| 5 | 34.1 | 8 | 3.8 | 27.1 | 6 | 3.9 | 11.2 | 2 | 3.7 | 8.3 | 1 | 4.2 | 5.3 | 1 | 2.7 | Green |
| 6 | 34.1 | 8 | 3.8 | 27.1 | 6 | 3.9 | 11.2 | 2 | 3.7 | 8.3 | 2 | 2.8 | 5.3 | 1 | 2.7 | Lab |
| 7 | 34.1 | 8 | 3.8 | 27.1 | 7 | 3.4 | 11.2 | 2 | 3.7 | 8.3 | 2 | 2.8 | 5.3 | 1 | 2.7 | Con |
| 8 | 34.1 | 9 | 3.4 | 27.1 | 7 | 3.4 | 11.2 | 2 | 3.7 | 8.3 | 2 | 2.8 | 5.3 | 1 | 2.7 | L.D. |
| 9 | 34.1 | 9 | 3.41 | 27.1 | 7 | 3.39 | 11.2 | 3 | 2.8 | 8.3 | 2 | 2.8 | 5.3 | 1 | 2.7 | Con |
| 10 | 34.1 | 10 | 3.1 | 27.1 | 7 | 3.4 | 11.2 | 3 | 2.8 | 8.3 | 2 | 2.8 | 5.3 | 1 | 2.7 | Lab |
| 11 | 34.1 | 10 | 3.1 | 27.1 | 8 | 3.0 | 11.2 | 3 | 2.8 | 8.3 | 2 | 2.8 | 5.3 | 1 | 2.7 | Con |
Notice how slowly the votes ('V') for Con and Lab go down as they get seats, compared to the other parties that had none to start with
