This is arguably one of the best 50min episodes of the entire series, and introduces Jim to the crooked face of International politics.
Bernard Hepton is superb as the MP with a murky past, engineering the convoluted plot and pulling all the strings in this tense plot.
The whole thing is rather let down by the ease with which the maveric SAS killer, Ian Redford infiltrates the security set up Jim puts into place to guard Ahmed. I would certainly have checked the boot of the car he had arrived in.
Excellent episode none the less. (edit)

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Avenge O Lord has its title from a poem by John Milton (1608-1674), which is also referred to in the episode. The poem was written as a commemoration of the massacre of the Waldensians by the Romish church in Piedmont, Italy.

Avenge O Lord thy slaughter'd Saints, whose bones
Lie scatter'd on the Alpine mountains cold,
Ev'n them who kept thy truth so pure of old
When all our Fathers worship't Stocks and Stones,
Forget not: in thy book record their groanes
Who were thy Sheep and in their antient Fold
Slayn by the bloody Piemontese that roll'd
Mother with Infant down the Rocks. Their moans
The Vales redoubl'd to the Hills, and they
To Heav'n. Their martyr'd blood and ashes sow
O'er all th'Italian fields where still doth sway
The triple Tyrant: that from these may grow
A hunder'd-fold, who having learnt thy way
Early may fly the Babylonian wo.

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