Nice bird...aviation history.
Started life as a de Havilland with a DH 125 designation.(and the fancy name of the Jet Dragon)
de Haviland was incorproated into Hawker Siddley company and the aircraft became the HS125, around 1963 Yeh a while ago now.
In time, 1978, Hawker Siddley was incorporated into British Aerospace Aircraft Group ...but the 125 series retained the HS designation....BAAG privatised into BAe around 1982 and at this stage the BA designation started to appear.
Later, 1993 BAe sold the design to Raytheon
So a little strange to see an 1985 aircraft with a HS designation, but this must refer to original certification, and not the aircraft delivered, which would be a BAe aircraft.