The hereditary peers can head for the polling stations after they were ejected from the House of Lords during the last parliament.
Before that happened they were, along with electoral fraudsters, "idiots" and "lunatics" (the criminally insane) and anyone serving a prison sentence, barred from voting rights.
It is a popular misconception that the Royal Family are also members of this select minority. In fact, they can vote if they wish, but do not because it could be seen as unconstitutional.
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At the other end of the social spectrum, for the first time homeless people were able to register to vote in time for this general election.
Another first is the scale of postal voting expected to take place. The number of electors who have applied to vote by post is thought to be up to two million - around a tenth of the electorate.
The government eased the rules allowing postal votes earlier this year, hoping to increase turnout as well as aiding the convenience of electors.
The move has proved controversial, however. The Electoral Commission announced at the start of the week that it would, after polling day, hold a review of the relaxed access and the potential for ballot-rigging.
But all votes enter the count at the same time once polling stations close at 2200BST.
The electoral system used for UK general elections is the first-past-the-post system - single member constituencies elected with a simple majority in each seat.
To win election as an MP, the successful candidate must gain more votes than any other individual contender in that constituency.
There is no requirement for a candidate to win a majority of the votes cast, which is the case in some electoral systems.
Unlike some countries, most notably those whose geography spans more than one time zone, the votes are counted immediately and by the following morning the party with most seats is clear.