Can someone tell me why the GWR website is trying to sell me a super off peak single Cardiff Central to London Euston via Birmingham on 24 Dec for £47.20 that for some reason includes a zone 1 London Underground fare? National Rail and Trainline tell me the ticket should be a flat £44.20. I don't want a London Underground ticket! I also don't want to pay the £1.50 booking fee on Trainline. ?!