Was this a legal way for a teacher to get information from a pupil?

[myriad]

A high school was investigating an incident of office break-in. There was no CCTV evidence. A pupil over-heard a conversation in which a name was mentioned which might be relating to the investigation. The pupil was in Focus Room for a completely different reason for that day when a senior school staff came in. The staff knew the pupil over-heard something, and insisted the pupil to reveal the name. The pupil believed it was just gossip and had no evidence to support the allegation. So the pupil replied that he was not at liberty to disclose the information. The staff became visibly annoyed and asked what the pupil thought he was "at liberty to disclose". The staff further elaborated by saying that he could prevent the pupil from going back to class after the pupil responded to him that going back to class was what the pupil wanted. The staff threatened the pupil with more disciplinary action if the pupil refused to comply. The staff also claimed that the pupil's action could have been interpreted as an "obstruction of justice".

The pupil was under pressure and feeling intimated, so he relented and gave the name.

My questions are:
- Did the pupil have the right not to disclose the information?
- Was it legal for a senior staff to use the actions and methods as mentioned above to get the information?
- Was the pupil's refusing really an obstruction of justice?


Thank you very much.
Myriad