Tony Richardson continued to insist on selecting filming locations, which he'd begun with A Taste of Honey (1961), the first British film to be shot entirely outside a studio. According to cinematographer Walter Lassally, location work was very difficult to sell to British film financiers at the time. "They were afraid that a lack of sunlight would delay the shooting interminably. It was impossible to convince them that for greater realism, it was actually desirable to shoot exteriors without sun."
There is a running scene in which the camera catches both the rising sun and the setting moon. Walter Lassally recalled a critic writing of this scene: "'What consultation of ephemerides there must have been to capture that precious moment'...which only goes to show that critics don't know a great deal about how movies are made, because you can't possibly plan a thing like that. It would take forever, and fall well outside your schedule." The shot was actually one of those happy accidents that sometimes happen in filmmaking. Two cameras were set up, one with a wide angle lens and one with a long focus. It was pure luck that the two celestial bodies were caught.
Tony Richardson's loose filming technique didn't always sit well with Tom Courtenay, even though the result seemed to be a perfect match of acting and directing styles. On the commentary accompanying the British DVD release, the now veteran actor says rather favorably that it sometimes felt like they were shooting a documentary, but in 1962 he noted his surprise, upon first seeing the film, at "just how sloppy and modern it looked" and how he learned on this production that "one of the skills in acting is to take from the director what he can give you that helps, and don't take any notice of what he does or doesn't do that upsets your performance."
Tony Richardson later noted that by not being based in a major studio, he was able to hand-pick his crew and get a much more enthusiastic group of colleagues together whilst still complying with union regulations.
The riot was largely improvised. There was one camera tracking up and down the aisles at the edge of the dining hall. Walter Lassally operated a second hand-held camera. His technique was to use the static camera and switch to hand-held at the exact moment everything turns violent or alive with frenetic movement, then cut back to static when the movement is less lively. "The choice, I think, of that moment where you switch from tripod or dolly to hand-held is very important," Lassally said.
Walter Lassally: "That was the only time I worked with Michael Redgrave, who is a lovely man. Super, he's one of those typical Englishman, you know, super polite and a very good actor, but very low-key. I think he was perfectly cast in that as the headmaster of the borstal.
According to cinematographer Walter Lassally, when production began, all the "spade work" had already been done, including all the decisions about where and how to shoot the film and all the technical details of the cinematic approach, because they had figured out most of that on the previous film he made with Tony Richardson, A Taste of Honey (1961). "So we went into Loneliness with relatively little preparation, except for the things that were demanded by the subject itself."
Cinematographer Walter Lassally brought many of the techniques he had discovered during the previous decade to his work on this film, such as the heightened realism that came from using minimal and primitive lighting instruments dictated by the cramped quarters of his locations, such as the Smith's home.
The musical score by John Addison incorporated some of the free-form jazz sounds current at the time. The score is most notable, however, for Addison's ironic use of the old hymn "Jerusalem" rendered in various styles.
Real borstal inmates were used as extras, primarily in the riot scene. Walter Lassally: "The mix was so good that you couldn't--unless you knew that this is an actor and this is an extra and this is a Borstal boy--you couldn't tell. The only time you could tell was at lunchtime, because they were absolutely ravenous. It looked like in the Borstal they were never properly fed because they were always looking. If you'd finished your dinner and you'd left something on your plate, they'd say, can I have that? ... They participated with great glee in the riot."
In his autobiography, Tony Richardson says his agent, Robin Fox, tried to discourage him from casting his son William Fox in the role of the race competitor from the rival school because he had no talent and it would be disruptive to his life for him to quit his job in a bank. It's not clear if this is entirely accurate because the younger Fox had been working fairly regularly on film and television since 1959. Nevertheless, Richardson gave him the role, which he played under the name James Fox, his professional moniker to this day.
The film was heavily sampled in the Chumbawamba song "Alright Now", and text from the book upon which the film is based formed the cover of their single "Just Look at Me Now" (a monologue starts in plain grey typeface on the front and another appears on the back).