Denis is a partner in Simpson Grierson's Resources and Infrastructure Department, which is comprised of the commercial property, construction, and local government and environment workgroups. Denis leads the commercial property workgroup in Auckland. 

He advises international businesses and individuals on the acquisition of, and investment in, New Zealand business and property. He also advises New Zealand-based businesses on trade and investment outside New Zealand.

In addition, Denis maintains an extensive domestic practice advising New Zealand-based clients on acquisitions, disposals, and investment in New Zealand business and property, property development, leasing, and land subdivision.

Denis has significant experience in dealing with the establishment and development of hotels both in New Zealand and overseas. Denis is the first New Zealander invited to join the United States based International Society of Hospitality Consultants.

He is the Honorary Consul of Mexico in Auckland. 

• Establishment of portfolio of properties for New Zealand Land Limited and subsequent sale to Kiwi Income Property Trust
• Establishment of Fletcher Homes and its acquisition of building companies throughout New Zealand
• Creation of a joint venture between American and Maori interests for acquisition and subsequent sale of a chain of hotels in New Zealand
• Establishment in New Zealand of Singapore based Dynasty Hotel Group
• Acquisition of the Carlton Hotel by Hong Kong-based interests
• Acquisition, development and sale of Hunters Plaza and Two Double Seven Broadway by Jen Retail Properties
• Purchase and subsequent sale of the Finance Centre in Auckland by Japanese interests
• Acquisition of a chain of supermarket properties throughout New Zealand for Macquarie Countrywide NZ Trust
• Overseas Union Bank's New Zealand financing of Gulf Harbour
• Whitianga Waterways and Marsden Cove developments for Hopper Developments

• Honorary Consul of Mexico
• Genesis Power - Director
• New Zealand Institute of Directors - Member
• Inter-Pacific Bar Association - Council Member
• International Bar Association - Member
• International Society of Hospitality Consultants - Member
• NZPECC - Board Member and Deputy Chair
• Asia Pacific Legal 500 2003/2004 - leading individual in the area of energy and natural resources, 2004/2005 - highly recommended in the area of real estate law, 2005/2006 - leading individual in the areas of real estate and construction law, 2006/2007 - leading individual in the area of real estate law