The venture has been named The Richmond Project after the area of North Yorkshire where former prime minister Rishi Sunak and Akshata Murty live.
Nicholas McMurray, 38, approached the 18-year-old woman on a Cardiff to Swansea train in June last year, British Transport Police said.
The King announced he had created his eldest son and heir, William, as Prince of Wales during his first televised address as monarch.