Universal suffrage, on an equal basis for men and women over the age of 21, was established in 1928.
Before 1918, general elections did not occur on a single day and polling was spread over several weeks.
A negative majority means that there was a hung parliament (or minority government) following that election.
No attempt is made to define a majority before 1832, when the Reform Act disenfranchised the rotten boroughs; before then the Tory party had an undemocratically entrenched dominance.
Particularly in the early part of the period, the complexity of factional alignments, with both the Whig and Tory traditions tending to have some members in government and others in opposition factions simultaneously, make it impossible to produce an objective majority figure.