Spa Valley would love to be able to give this guarantee, especially on Green days however steam locomotives can and do from time to time decide that chuffing up and down the countryside isn't for them. They can sometimes even have a fault develop during the day and have to be withdrawn from service, this is the last thing we want to do but passenger safety is of paramount importance so whilst we'd love to guarantee a steam locomotive will pull your train when advertised it isn't always possible.