There is an analogy with Goldman Sachs' ownership of LME warehouser Metro and its role in the aluminium market.

The warehouser of chilled fruits, vegetables and meats delayed the IPO and cut its value by 7 percent before yanking it.

Warehousers say this tough new stance is scary enough to work.

But for those warehousers at the top of the metals storage game, it's boom time, with sheds full and queues long.

They will be sued by warehousers if they make any changes or by consumers for denying access to metal, said another Swiss trader.