According to the Daily Telegraph:
“The Scottish aristocrat, a close friend of Princess Margaret, who owned a swath of land on the Caribbean island of St Lucia, held his assets through an offshore company, Beau Estates.
Lord Glenconner, who died in 2010, frequently hosted the Queen’s late sister on glamorous trips to the Caribbean.
After he died, Glenconner’s family were surprised to discover that he had left his shares in Beau Estates to his manservant, Winston Kent Adonai, and fought the will. Beau Estates was set up in Panama in 1988 before being transferred to the BVI.
The original documents show that the company was controlled by “Mr Lord Glenconner”.”
There has been no indication however that the offshore account was used to shelter assets to avoid tax or to cover any illicit transactions.