I always thaught "Borstal" was any institute for young offenders and not just the name of one particular place.
My brother and his friend went to Borstal as kids. The friend cried himself to sleep every night but my brother said he quiet enjoyed it.
As the Wikipedia entry suggests but doesn't directly state it's both. The first "Borstal" was in the Kent village of Borstal but it has since become a generic term of a young offenders institue.