He is devoted to the preservation of Britain's national security, but while battling the KGB, his main sources of antagonism are the people on his side: superiors in SIS, whom he alternately considers too cautious or too reckless; self-serving politicians who grant or withhold permission for his covert operations; territory-hungry MI5 officers; and entrenched civil servants.
His single-minded devotion to his job cost him his marriage before the start of the series, though he maintains a close relationship with his former father-in-law, Sir Geoffrey Wellingham, the Permanent Undersecretary of State at the Foreign and Commonwealth Office.
A fluent French speaker, Wallace develops from new recruit to seasoned veteran over the second and third series, even successfully undertaking a dangerous mission to rescue a wounded CIA operative trapped in Sukhumi (then part of the USSR).
Burnside puts his career on the line to protect Wallace from a vengeful station chief in the second series episode "A Question of Loyalty".
Sir Geoffrey Wellingham, KCMG, DSC is the Permanent Undersecretary of State at the Foreign and Commonwealth Office that oversees SIS.
Unlike Burnside, Peele has little field experience and is more concerned with avoiding in-fighting with MI5, keeping politicians happy, and furthering his ambitions to higher rank.
As a result, Peele often stands against what he sees as Burnside's recklessness, contempt for the proper chain of command, and lack of political tact.
At times Peel comes off as an aloof Englishman, preoccupied with ancient history and gardening, though on several occasions he shows himself to be sharper and more ruthless than he lets on.
He is disliked by his subordinates and considered weak-willed and easily manipulated, but proves himself just as committed to the security of Britain as Burnside; their relationship evolves over the course of the series to one of mutual respect (if still antagonistic).
The two often have lunch and work together to preserve the "special relationship" between the CIA and SIS, and Ross takes an interest in Burnside's (non-existent) personal life.
She initially views the Sandbaggers, and other such units around the world, as playing "cowboys and Indians" and perpetuating conflicts between countries, in particular between East and West.
However, she slowly warms to both the Sandbaggers and Burnside personally, and the two begin a romantic relationship, albeit a complicated one due to psychological trauma in her past.
Karen Milner (Jana Sheldon) is a CIA field officer who reports to Jeff Ross and sometimes works alongside one or more of the Sandbaggers; she is only seen in the second series.
After Tyler's suicide, he is replaced as D-Int by Paul Dalgetty (David Robb), an arrogant and considerably less capable officer who has a completely antagonistic relationship with Burnside.