Originally called to the Bar, Lex quickly transferred to leading City shipping law firm Holman Fenwick & Willan and qualified as a solicitor. He subsequently worked in-house for Coastal States, a large  Houston based oil trading house, before moving to the Lloyd's Market as Claims Manger for reinsurance broker R K Carvill. Returning to private practice he became a partner in Taylor Garrett (now Taylor Wessing) and then left London for family reasons to join what became the Newcastle office of Eversheds, where he was Head of the Litigation Department. He joined Simpson & Marwick in 2004 and set up the firm's first English office in Newcastle in 2011.

Having started as a dry shipping, international trade and marine insurance lawyer, Lex is now best known as a leading occupational disease lawyer and insurance law expert, acting for British Shipbuilders and other public institutions, and for a range of corporate and insurance clients. Lex has been recognised by the Legal 500, 2016 as a recommended lawyer.