MightyGem
The ground designation for LGB attacks in the Falklands was carried out by a TACP with the Welsh Guards, under the command of Major Mike Howes, calling himself Green Dragon on the radio. Presumably your brother-in-law's colleague was part of this TACP?
The whole story of the Falklands LGB saga, (including the Navy's screwing-up of the attempted live trial in theatre), is contained in Pen and Sword's RAF Harrier Ground Attack Falklands by Jerry Pook