Looking for an 80s/90s series where teenage boys were being trained in the military on a remote island

I'm hoping someone here knows this series, it came to me in a flashback early this morning.

I've been googling all morning, but so far no luck.

It was in the late 80s/early 90s, and IIRC, it was a (perhaps british?) tv series with young boys on a remote island being trained in the military. They all had shaved heads, dressed in black, and I recall a scene with a black helicopter chasing one of them in trenches/across a field.

Does anyone here perhaps know the name of this series?

Thanks