Tax
Don't forget that if you give the money to charity as Gift Aid then you/they get the tax back in the end. For example, if you receive £100, the Revenue take £40 of it, you then give the remaining £60 to the charity. They claim back some of the tax and you can get the remainder back in your tax return. And give that to them too, if you're feeling generous.
Edited when my sums didn't add up!