The start-up, to be called Brandpool, will service its business by using independent and freelance talent and claims it is willing to work with other agencies if necessary to provide a comprehensive service to clients.
Southern, which serves the south coast and South East to London lines, is putting £1 million behind an initial burst of activity that will break in London and regional press and posters over the next month. M J Media will handle media planning and buying. Brandpool will act as a communication adviser to the company as well as creating and managing advertising and other communications.
Southern is keen to promote a three-year period of change that it claims will go beyond the running of new trains and repainting stations.
McWilliams, who was the managing director of Arc before its sale to Bates UK, has closed Jojo, the brand consultancy he set up four years ago, to launch Brandpool.
He claimed his new operation would be more flexible and adaptable than the conventional agency format and did not rule out bringing other agencies into the ser-vice "pool".
"It's about seeing other agencies as potential collaborators rather than automatic competitors," he said.