Renovation and Profit

My friend brought a run-down house in the West Country and over last summer he asked me if I would help him with the building work. Over the course of three weekends we managed to replaster the whole interior and install a bathroom. It was hard work but I knew that living in the country had always been his and his wife's dream and I wanted to help him achieve that. I have just learned that my friend has put this house on the market after living in it for only a few months, and that he will make a substantial profit. I feel a bit put out! I put in a considerable amount of work and saved him a lot of money – am I am due some part of the profits?