You’d think a film about the rise of a famous British rock ’n’ roll band of the 1960s and ’70s would be fascinating. And if that band was named The Who, you’d think the word “Who” would be in the film’s title.

Not that the two parties can be easily separated, but the documentary “Lambert and Stamp” ostensibly is more about The Who’s managers, Kit Lambert and Chris Stamp, than Pete Townshend, Roger Daltrey, John Entwistle and Keith Moon. Townshend reckons Lambert and Stamp are the fifth and sixth members of The Who.

Promising ingredients are in “Lambert and Stamp,” but the film wanders off key. It’s variously redundant, even frustrating. Chronologically, the storytelling needed better management. An 80-minute film would have been better than the existing two-hour film.

Odd-couple Lambert and Stamp met while they were working at England’s Shepperton Studios as second assistant film directors. Knowing they were unlikely to ever become the full-fledged directors they wanted to be, the pair searched for a rock ’n’ roll band to film. Lambert and Stamp planned to use their cinema vérité documentary about the group’s rise to stardom as a ticket to directing careers.

The documentary was never completed. Lambert and Stamp grew too busy managing The Who. They also contributed to the group’s music, recordings and stage presentation. The always incendiary Who, after years of not being modestly successful, exploded into major popularity in 1969 with their rock opera, “Tommy.”

Director James D. Cooper incorporates cool black-and-white footage that dates to the beginning of The Who’s partnership with Lambert and Stamp. This early footage includes film Lambert and Stamp shot of The Who, then named The High Numbers, for the intended documentary. For instance, the band is seen and heard in a crowded venue performing New Orleans singer-drummer Jesse Hill’s 1960 hit, “Ooh Poo Pah Doo.”

The documentary also contains extensive, recent interviews with Stamp, who died in 2012 at 70, and interviews with surviving Who members Daltrey and Townshend, who are currently on a 50th anniversary tour.

No one thought The Who would last, Townshend says in a recent interview. “I had this idea that it would deliberately blow itself up.”

Lambert’s troubles included alcoholism and heroin addition. He died in 1981 at 45, three years after Moon, his most ardent supporter in The Who, died at 32 of a drug overdose. “Lambert and Stamp,” however, features much 1960s footage of Lambert, including interviews the Oxford-educated son of a symphony orchestra conductor gave to European radio and TV.

While Lambert was posh, Stamp was working-class rough. The son of a tugboat captain, he’d grown up in London’s East End. Despite the class distinction between them, the documentary explains, Lambert and Stamp both felt like outsiders whose artistic ambitions had been thwarted. They wanted to become someone that society, or at least the film world, said they could never be.

Exhaustively try to express the universality of such dreams and desires, “Lambert and Stamp” only sometimes succeeds in doing so.

“Love is given,” Stamp says in 2008, on the occasion of Daltrey and Townshend being awarded the Kennedy Center Honors. “We were there for each other, in an unheroic way, in a sensitive, frightening way.”