Hundreds of corporate insolvencies that have been frozen because of legal uncertainty over who ranks first for repayment will move a step closer to resolution today when Britain's highest court starts to consider a landmark test case.

An unusually large panel of seven law lords will consider the so-called Spectrum case, in which National Westminster Bank is claiming that the type of security that it held over book debts at Spectrum Plus, a paint company that went into liquidation in 2001, counted as a "fixed" rather than a "floating" charge.