Managed to get contact details for the Royale de Luxe company from Nantes Tourist office - in case anyone wants to find out more about future programmes. The office is closed at the moment - re-opens 15 August - otherwise I would have posted more information myself.
Phone number is: 0033 2 40 20 44 85
Email is:
royale.de.luxe@wanadoo.fr
Hope above is of use to others like me who want o know about the London planned visit.
Cyclefrance