I put my anorak on and this is what I remembered
G-TIGB Britoil (Thistle)
G-TIGC Amoco (NW Hutton)
G-TIGD Amoco (NW Hutton)
G-TIGE Marathon (Brea)
G-TIGF Britoil (Thistle)
G-TIGG Marathon (Brae)
G-TIGH Amoco (NW Hutton)
G-TIGI Mobil (Beryl)
G-TIGJ Conoco (Murchison)
G-TIGK Conoco (Murchison)
G-TIGL Hamilton Bros (TW58)
G-TIGM Britoil
G-TIGN Phillips (Maureen)
G-TIGO Mobil (Beryl)
G-TIGP BP
G-TIGR Amoco
G-TIGS Mobil
G-TIGT ?
G-TIGU Conoco?
G-TIGV Conoco?