The tough-talking South African and the BHPB board simply described his departure as "irreconcilable differences" - code for the CEO not getting on with the bureaucratic way BHPB has traditionally behaved.

BHPB chairman Don Argus said in a statement that he wished Gilbertson "every success in the future" - and immediately named the company's chief financial officer, Chip Goodyear, as chief executive.

The 44-year-old Goodyear was an appointment of Gilbertson's predecessor, Paul Anderson, indicating that the Anderson style of management is more acceptable to the BHPB board that the more aggressive Gilbertson style.

Issues which would almost certainly have come up at board meetings and created tension between the deeply conservative Australian members of the board with Gilbertson include:

* Enhanced exposure to South Africa, Gilbertson's home country and one in which he feels confident, which some outsiders view as a larger Zimbabwe-in-the-making.

* Ongoing commitment to the loss-making HBI (hot briquetted iron) plant which Gilbertson would like to close but the board feels should be kept open because of the complexity of a "take-or-pay" gas supply contract with Woodside Petroleum.

* Committing more company funds to the oil division of BHPB when Gilbertson is a traditional "hard-rock" man.

* Disagreement on a fast "first-strike" at WMC. Gilbertson has always moved fast and sorted out the problems later. The BHPB board is much slower to act, especially after a string of takeover failures in the 1990s.

* Complying with an undertaking that the CEO will live in Melbourne when Gilbertson has acquired a luxury home in London, and his family is said to prefer London and Johannesburg to Melbourne.

* Unhappiness at a board level with Gilbertson's powerful personal style which goes from a desire to do quick deals to having a big picture of Bridget Bardot on his office wall - very much a no-no in the austere Melbourne business world.

* Age, and a desire by Gilbertson to get a long-term contract, or be free to enjoy life. He is 57, old for a newly appointed CEO. He is also rich. There has been speculation that the BHPB board saw him as a short-term appointee, effectively the Billiton man serving his time at the top after Anderson (the BHP man) did his stint.

Whatever the reason for Gilbertson's sudden departure it is in keeping with Gilbertson's style - crash-through or crash.