Sebastian specialises in advising wealthy families on tax and succession issues. Much of his work has an international dimension and many of his clients have no connection with the UK.

He advises on the creation and operation of asset-holding structures and family offices. He also advises on tax investigations and litigation involving family trusts.

Sebastian advises many UK and non-UK based families on their tax position, both in the UK and internationally. In 2003 he spent six months on secondment with the trusts and estates group of a leading New York law firm and, as a result of this experience, much of his work has a US dimension.