Can anyone help me with my Government and Politics A-Level query?

This will be easier to understand using an example. Imagine a town (we’ll call it Fluthertown) which has 10,000 voters (all of whom vote in every election). Now let’s say Fluthertown is in a country using the form of government described above in your question and that Fluthertown is assigned three seats in the national legislature. Under a system of proportional representation, the electorate votes for a party rather than a candidate. So in order for your party to get a seat in the national legislature representing Fluthertown, your party has to meet a certain threshold of votes (the “quota”). That threshold is determined by taking the total number of votes (in this case 10,000) and dividing it by one more than the total number of seats to be filled (in this case, with three seats to be filled, we divide by 4). So, in Fluthertown, if you want to win a seat for your party you need at least 2,500 votes.

Imagine the following hypothetical vote totals:

Party A – 5,000
Party B – 3,000
Party C – 1,500
Party D – 500

Now one might think that because of the order of the vote totals, Parties A, B and C all get one of the Fluthertown seats. But, no. Party C was unable to pass the 2,500 vote threshold, so the Fluthertown seats will be divided up between Parties A and B only (in this case, depending on the specific laws, Party A would likely get two of the three seats). This threshold is in place to prevent very small parties from gaining seats. Imagine the following results:

Party A – 8,000
Party B – 1,000
Party C – 550
Party D – 450

Without the threshold, Party B would probably claim one third of the seats even though they won only 10% of the vote.

Ordinarily, this system is used in large constituencies with many seats. In Israel, for example, the entire national legislature is elected this way from one big constituency (meaning that there are no regional representatives).

Thank you. That really helps! Much clearer now.