Thank you very much Mr Migky. Just been on the phone to my dad, and he's really pleased that you've found that information. He was positive Francis was in the Lancashire Fusiliers.
Have done a search for his service records in the past on Ancestry but nothing showed up, when I saw your kind offer I thought perhaps there's a chance to find his medal card from that information as my dad remembers his grandad (Francis's son) showing him a few medals.
Just been having a look at the medal card on Ancestry, there's something that says "SW B List K/6Y3/2" alongside mentions for the 15 Star, Victory and British, so not sure what that refers to?
William died young so didn't serve, but he had another brother called James born 1870 who did. Yes, definitely the right family, thanks again so much.