The MacKintosh Man (1973) on Netflix

Joseph Rearden is going undercover for the British Secret Service. The only people who know about the undercover work are Rearden's director, Angus Mackintosh, who he trusts implicitly, and Mackintosh's assistant, Mrs. Smith. The set-up: Rearden, posing as an Australian tourist in Britain, will be caught and convicted of a £140,000 diamond theft, the jewels which are never recovered (since Rearden will pass them on to Mrs. Smith and Mackintosh). The "on the surface" plan is for Rearden to infiltrate a group known as the Scarperers, who assist long term inmates escape, the unrecovered diamonds as the financial bait. Things do not go quite according to plan, with a leak somewhere in the informational chain as Mackintosh and Mrs. Smith are supposedly the only people who know officially what's going on. However, in reaching the true end goal, Rearden is unaware of a second plan concerning Mackintosh and longtime Conservative Member of the British Parliament, Sir George Wheeler, who is best known for his frequent political diatribes on the British government not doing enough to protect itself from foreign threats.