I travelled the other day 3 adults and was offered a groupsave discount of 26% no Railcard needed, was told 3 or more qualifies but, not all train companys offer it , you have to ask, anyway checked on Trainline app for 3 adults travelling in Cornwall and it added the groupsave discount automatically, don't know if it's regional. The gwr and cross country apps had it in the Railcard section but you had to select it yourself.
Anyone know if you can stack these - current one expires August?
Full range here. Take a look at the Two Together. Hyperlink not obvious due to colour so: https://www.railcard.co.uk/
The code is in the description, about halfway down in bold. It's EST20GA.