Strictly speaking, either the bride or groom should be resident in the commune where the marriage is to take place for a period of not less than 40 days immediately before the wedding. Where it is the parents of either the bride or groom who are the residents, the interpretation of the residency requirement is up to the mayor of the commune. In our case the mayor decided that as we are full-time residents of several years standing, and our daughter has been a frequent visitor during that time, the marriage could go ahead. If the prospective bride or groom are non resident, or part-timers, then it would be wise to talk to your mayor at the very beginning to see how the land lies. If it looks as if there will be problems then it is always an option to have a civil ceremony in the UK, followed later by a religious service - if wished - and the reception in France.