i newspaper, May 27, 2017
Some group nouns can be treated as singular or plural, for example ‘the jury was told’ or ‘the jury were told’, and often it comes down to a matter of which sounds better. I feel that the smaller the number, the more likely that treating the noun as plural is the better choice, because you visualise the group as a number of individuals. Some authorities differ, but I can’t bear ‘The couple was . . .’ Anyway, the one thing you can’t do is to mix singular and plural. Here we have ‘ . . . did not do enough to protect them’ and ‘The royal family was killed’. Obviously you could not have ‘ . . . did not do enough to protect it’ so the last line should have been ‘The royal family were killed’.
See ‘singular or plural?’ in Style Matters: