Within a year I was back at work on something utterly different, still for television, but this time made entirely inside a studio. It was Sapphire and Steel. Taxi drivers sill say to me, ‘You know that Sapphire and Steel? It really scared me.’

…

David McCallum was perfect in the part of Steel. (“Software and Steam” was the show’s nickname.) He has “heart-throb’ tattooed on his features; after working so closely with him for two years I would have also added ‘brainbox.’ He and P.J. and our director Sean <sic> O’ Riordan would huddle together working on the scripts to make them more gripping and terrifying.

….

From Sapphire and Steel I learned the techniques television acting, how to use your face to tell a story. McCallum always insisted that if you had to portray a sudden idea coming to your mind, or a realization, something vital was about to happen, you must always glance up—just for a split second: up.

From Joanna Lumley’s biography by Tim Ewbank & Stafford Hildred

“All irregularities will be handled by the forces controlling each dimension.” (And etc.) It’s another chapter of Joanna’s career.

Joanna’s character, Sapphire, and Steel, played by David McCallum, were two elements sent to earth by a universal power to try to contain a negative force, responsible for all disturbances in the natural order. Steel was the macho, hard-nosed technocrat, a strong being. who could block tremendous forces with his body and exert great powers…Steel wore a grey flannel suit, while Sapphire was always dressed in blue.

Long story short: the producer (Shaun O’Riordan) wants star casting and comes up with some fancy names “and one of them was David McCallum.”

I said: “You’ve got to put a woman with him who’s magic,” and then Joanna’s name came up. “There was no doubt in my mind. I sent the scripts to both of them and they both said yes.”
…

Joanna was intrigued by this ‘rather different kind of mystery series’ and delighted to be off on another major series again, particularly alongside an established star such as David McCallum who, she noted charitably (transcriber’s note: charitably!!) had hardly changed since he broke so many female hearts as charismatic Illya Kuryakin on The Man from U.N.C.L.E.

…

The chemistry between Joanna and David McCallum worked from the start and the pair of them became friends. Shaun O’Riordan said: “I could never work out if they were having an affair or not because they used to have breakfast together. I used to try to get information but I never found out.

“But Joanna used to smoke Gauloises and David was the most fastidious man. He wouldn’t eat salt with his food, he limited the amount of fat and looked after his body. He took care of himself so smoking was an absolute anathema to him.”

In fact David McCallum and Shaun O’Riordan became great friends, something Joanna found difficult occasionally.

“Joanna regarded McCallum and me as a kind of male Mafia. She thought we were bullies, determined to run the show as we thought should be run and ganging up on her. But we were just trying to get it right. I can remember sitting on the floor of my office with McCallum, a pair of scissors and a blue pen cutting up pages of the script, rearranging them and trying to get a sort of end to the first series.”

…

“Of all the actors I have worked with, McCallum is the one who remained a friend. My first wife loved him dearly and even now, every time he comes to England he comes and stays.”