I think potted history is something like this.....
N2961W
VR-BEK
G-BALZ 10/01/1973 - 05/03/1973 Oxford Heli-Services Ltd.
EI-AWK 05/03/1973 - 16/07/1974
G-BALZ 16/07/1974 - 10/01/1977 British Executive Air Services Ltd.
N99040 10/01/1977 - 18/03/1977
G-BALZ 18/03/1977 - 19/10/1979 British Executive Air Services Ltd.
N8069A 19/10/1979 - ??/??/????
VR-BIB ??/??/???? - 12/05/1982
G-BALZ 12/05/1982 - ??/??/???? British Executive Air Services Ltd.
G-BALZ ??/??/???? - 03/03/1994 Bristow Helicopters Ltd.
9Y-TIL 03/03/1994 - 17/02/1995
G-BALZ 17/02/1995 - 07/06/1995 Bristow Helicopters Ltd.
EC-931 07/06/1995 - ??/??/????
EC-EGR ??/??/???? - 03/10/1995
G-BALZ 03/10/1995 - 30/05/2003 Bristow Helicopters Ltd.
EC-IPD 30/05/2003 - 30/09/2003
G-BALZ 30/09/2003 - date Bristow Helicopters Ltd.
Mike