Christina Domecq, the scion of the sherry dynasty, is being sued by the US group that bought her troubled technology start-up.
Nuance Communications paid $102.5m for SpinVox in 2009, though the UK-based group had been worth five times that.
However, the group, which converts voicemails to text messages, was hit by allegations over the way the messages were transcribed – using workers in India rather than state-of-the-art technology, a claim SpinVox rejected – and losses. Ms Domecq later repaid £125,000 in expenses.
Nuance issued a High Court writ last week, with SpinVox also named as a plaintiff. Nuance declined to comment and Ms Domecq did not return calls.