Isabelle de Warrene

Extract from William Fitzstephen. Materials iii, p. 142

...
Eum procumbentem Ricardus Brito percussit tanta vi ut et gladius ad caput ejus et ad ecclesiae pavimentum frangeretur, et ait, 'Hoc habeas pro amore domini mei Willelmi, fratis regis.' Hic siquidem Willelmus appetiverat conjugium comitissae de Warrena, sed archiepiscopus contradixerat, quoniam hic Willelmus ex matre imperatrice Mahalt, ille comes Warennae Willhelmus ex patre rege Stephano, consobrinorum fuerant filii. Unde Willelmus, frater regis Henrici, inconsolabiliter doluit et omnes sui archiepiscopo inimici facti sunt.
...

And whilst prostrated Richard Brito struck his head with such a force that both his sword and the paving of the church cracked, and he said, "You may have this for the love of my lord William, brother of the king." This all followed  from the marriage of William had desired with the Countess of Warren, but which the archbishop had opposed, since this William's mother was the Empress Matilda, and Earl William Warren, his father was King Stephen, it followed they were children of cousins. Hence the soul of William, the brother of King Henry,  was inconsolably grieved, and this made all of them enemies towards the archbishop.

References

House of Warren - Wikipedia

Keith Sidwell (24 August 1995). Reading Medieval Latin. Cambridge University Press. pp. 317–. ISBN 978-0-521-44747-8. 

http://en.wikipedia.org/wiki/Isabel_de_Warenne,_4th_Countess_of_Surrey