How does George MacDonald Fraser use imagery in Flashman in the Great Game: From the Flashman Papers 1856-1858?

Examples of Imagery:

"While the drum beat slowly, a havildar and two naiks went along the ranks of the prisoners, tearing the buttons off the uniform coats; they had been half cut off beforehand, to make the tearing easy, and soon in front of the long grey line there were little scattered piles of buttons, gleaming dully in the sultry light; the grey coats hung loose, like sacks, each with a dull black face above it."

"Groups of armourers, each under a British sergeant, went from man to man, fastening the heavy lengths of irons between their ankles; the fast clanging of the hammers and the drum-beat made the most uncanny noise, clink-clank-boom! Clink-clank-boom! and a thin wailing sounded from beyond the ranks of the native infantry."

"He apologised in a nervous whisper, and muttered something about Queen and Country; his eye was glittering feverishly. 'Oi'll be more discreet, Flash,' says he, and so we went on, with me answering another couple of challenges before we reached the bridge, and crossed safely over into Lucknow town."