Children's series, boarding school, possibly aliens not Roxwell

[Somni]

I'm trying to recall a children's (young adult, I guess) series set in a boarding school. Read about 15-20 years ago, I thought the first in the series was "Ghosts of Buxton (or possibly Brampton) Hall" but this has produced no results.
The books involve a small group, mixed sex, of students at a boarding school.

The only plot elements I (think I) can remember are that they do something to help a student who's parents turn out to be aliens. The dad then hypnotizes the students of the whole school to help them pass an inspection, but they got the date wrong so have to close the curtains and adjust the clocks to push the students body clocks round so they believe the inspection is on the day they were hypnotized to behave on.

Sorry if that is a bit muddled by I struggled to phrase it well.

I am sure there were at least three books in the series, and that the students had at least two boys and a girl in the group. I don't think it was the Roswell T.V. programme as I think it was set in the UK and earlier than 1999.

I hope someone can help.

[pinky]

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