Definite article versus no determiner
With nouns of time
British English may use the in certain expressions of time where American English would have no determiner.
all the afternoon/morning/evening All afternoon/morning/evening: The forms without the are common-core English. CIC has 5.9 iptmw with the in British texts but none in contemporary American use. <I slept all the afternoon.> 1970 Johnson 18.
all the day long All day long: The definite article is optional in British use (CGEL 8.63n). CIC has 0.3 iptmw of the phrase with the in British texts and none in American.
the month The implication of this construction, without any posthead modifier, is “this month of some implied year.” In a random sample of 150 tokens of January in CIC British texts, 6 were preceded by the; a similar American sample had none. <A settlement … was proposed by the MPs in the June, before the legal costs had started to mount.> 1986 Oct. 19 Sunday Times 1/2.
the date of a month; month the dateMonth date: See § 17.4.
in the night At night: CIC has nearly twice as many British tokens of in the night as American; at night is nearly 6 times as frequent as in the night in British texts, but nearly 10 times as frequent in American. < … he gets up in the night for [his child].> 1993 Neel 70.
the once Once: The adverbial use of the once is about 14 times more frequent in British than in American. <Well, just the once.> 1989 Rendell 31. Cf. § 6.1 once.