Nairn is a very wily operator, whilst trusted on the whole by Wellington, he nevertheless holds his ground with his peer, and also with Sharpe, in several scenes although he is tactful and quietly spoken, when he is against opposition, be it Wellington, Sharpe or an English colonel with much authority, he does not back down, nor give way but fights to put his point across.
Of all Wellington's exploring officers, Nairn is probably the hardest in character, although he does have a soft spot for Richard Sharpe. But he won't let him have his own way, and they often argue, especially in Sharpe's Company. There is a wonderful scene in Company, when Sharpe who is in despair and angry because his captaincy has been taken by Rymer, complains to Nairn, and tells him that soldiers shouldn't shovel or count lists - Nairn loses his temper and replies, "How did you get to be an officer Sharpe, except for counting heads and making lists, it is soldiers' work, not all soldiers can swan about like you do!".