It's taken from a poem by T.S. Eliot called "Burnt Norton," the first of his "Four Quartets." The lines it comes from are:
"Garlic and sapphires in the mud/Clot the bedded axle-tree./The trilling wire in the blood/Sings below inveterate scars/Appeasing long forgotten wars./The dance along the artery/The circulation of the lymph/Are figured in the drift of stars."
The title is actually taken from the title of the book 'Wire on the blood' by Val Mcdermid who writes the Tony Hill novels. It was the first one to be done on TV