The Welsh freedom-fighter Owain Glyndwr’s daughter Catrin and her children were captured by the English at the Siege of Harlech in 1409. They were then brought to London and imprisoned in the Tower, and at least most if not all of them died there in 1413, under circumstances best described as “mysterious” (*). Surviving records indicate that Catrin and two of her daughters were buried not in the Tower but in the churchyard of St Swithin London Stone on the other side of the city (there are no records of what became of her other daughter or of her son Lionel).
A modern Gelligaer bluestone sculpture by Nic Stradlyn-John and Richard Renshaw, inscribed with a Welsh englyn by Menna Elfyn, marks the spot. Freely (by me) rendered into English, the englyn reads: “In the Tower, now her home,|Her heart-song turns to longing:|The exile’s silent lament”.
(*) The children had a claim to the English throne through their late father Edmund Mortimer (who was descended from Edward III). Some suspect that they were done to death so as to prevent them from making any such claim.