I finally got around to looking up a quote from The Impossible Planet in Doctor Who and found out that it's from a huge, docking great poem called Horatius by Thomas Babington Macaulay. The whole poem can be found here, and below is the stanza containing the few lines spoken in DW by Mr Jefferson.
Horatius (from the Lays of Ancient Rome – 1842)
Verse XXVII
Then out spake brave Horatius,
The Captain of the gate:
‘To every man upon this earth
Death cometh soon or late.
And how can man die better
Than facing fearful odds,
For the ashes of his fathers,
And the temples of his Gods,