So I went to London from Weymouth last weekend booking using the £15 SWR single offer. However railcard discounts do not work on top of this. What is the explanation behind this? Personally I think that railcard discounts should be able to be used alongside the special offer, else it seems increasingly pointless buying railcards, especially since a railcards primary use is for off peak travel (weekends and holidays) , which often coincides when TOC's release offers.