Date and time notation in the United Kingdom

Dates are traditionally and most commonly written in day–month–year (DMY) order:[1][2] Formal style manuals discourage writing the day of the month as an ordinal number (for example "31st December"), except with an incomplete reference, such as "They set off on 12 August 1960 and arrived on the 18th".

[1][3] When saying the date, it is usually pronounced using "the", then the ordinal number of the day first, then the preposition "of", then the month (for example "the thirty-first of December").

The month-first form (for example "December the third") was widespread until the mid-20th century and remains the most common format for newspapers across the United Kingdom.

The 24-hour notation is used more often than in North America – transport timetables use it exclusively, as do most legal documents – but not as commonly as in much of the non-English-speaking world.

[citation needed] The spoken 24-hour format is used in airport and railway station announcements: "We regret to inform that the fifteen hundred [15:00] service from Nottingham is running approximately 10 minutes late"; "The next train arriving at Platform four is the twenty fifteen [20:15] service to London Euston".

For 12-hour time, the point format (for example "1.45 p.m.") is in common usage and has been recommended by some style guides, including the academic manual published by Oxford University Press under various titles,[8] as well as the internal house style book for the University of Oxford,[9] that of The Guardian[10] and The Times newspapers.

The more descriptive 2014 revision of New Hart's Rules concedes that the colon format "is often seen in British usage too", and that either style "is acceptable if applied consistently.

The abbreviation can cause misunderstanding with non-native speakers as this contrasts with many European languages, where the same type of expression denotes 30 minutes before the hour.

For example, Czech půl desáté, German halb zehn, Finnish puoli kymmenen, and Swedish halv tio (all literally "half ten") mean 9:30.

Phrases such as y bore ('(of) the morning'), y prynhawn ('(of) the afternoon') and yr hwyr ('(of) the evening') are used to distinguish times in 12-hour notation, much like Latin a.m. and p.m., which are also in common use, for example 9.00yb (09:00) as opposed to 9.00yh (21:00).