Yes indeed I do, as I thought it was valid and therefore when I was told incorrectly by Paddington ticket office that it wasn't valid, proceeded to buy it and travel. I have since submitted a complaint to them. Gateline staff said it was valid too. I have other qualms with GWR such as their ticket machines not letting you buy child tickets without adult tickets, and retaining tickets on return journeys. It is all in the complaint to GWR.