Often, the music is not clearly one time signature or the other but rather a beautifully ambiguous combination of the two.
Then the drums come back in, perhaps now playing a different time signature.
Grime smacks and bullies whatever time signature it is grudgingly participating in.
However, when the lifetimes are close to each other, the clues in the time signature alone are not decisive.
British Dictionary definitions for time signature
(music) a sign usually consisting of two figures, one above the other, the upper figure representing the number of beats per bar and the lower one the time value of each beat. This sign is placed after the key signature at the outset of a piece or section of a piece