African-American actor, singer, dancer and activist Harry Belafonte – now 85 years of age – makes a fascinating subject in an expansive documentary which functions for much of its running time as a vibrant slice of American civil rights history.

With a gruff Belafonte also narrating, it comes as no surprise to find that Sing Your Song is hardly a critical piece, and at times tantamount to auto-hagiography. However, such an indulgence can be forgiven when the subject has lived an extraordinary life and has so many amazing stories, freighted with socio-political significance, to tell.

Though his artistic endeavours are paid due attention in the film’s early scene-setting passages, Sing Your Song’s focus is placed firmly on Belafonte the activist. Inspired by the trailblazing black American singer Paul Robeson, Belafonte developed a political consciousness at an early age which further developed when he became the target of racism in the American south, and encountered discrimination as an artist.

Throughout the 1960s, his influential presence is a constant in a tumultuous era which witnessed the assassinations of John F. Kennedy, Martin Luther King, Bobby Kennedy, the Vietnam war and a rapidly changing media landscape.

Distinguished by some exceptional archive footage (both of Belafonte’s performances and of the American Civil Rights movement), propulsive editing and a willingness to investigate the difficulties that activism poses to a healthy family life, Sing Your Song is also notable for its exploration of the putative intersection between celebrity and activism.

We now live in age in which it’s easy to be cynical about celebrity engagement with political causes, but it’s hugely impressive and bracingly refreshing to see Belafonte’s influence on John F. Kennedy, and his closeness with civil rights leaders Martin Luther King and Nelson Mandela. Furthermore, it’s quite something to see a celebrity advocate coterie comprised of the likes of Belafonte, James Baldwin, Marlon Brando and Charlton Heston.

This always watchable film falters toward the end in its eagerness to document the vast, globe-spanning canvas of Belafonte’s activism at the expense of really drilling down into what makes its inspirational subject tick. The sections devoted to the US civil rights struggle of the 1960s are powerful, detailed and pointed, but as Belafonte travels to Iraq, South Africa, Germany, and even modern-day L.A., it all starts to feel a bit like a vague, extended infomercial with Belafonte in the role of activist Zelig.

Belafonte is heard in a recent conference to stress the importance of “defining the agenda”. Though it’s never a chore to spend time in the company of this one-off figure – and all of this is clearly being done to highlight Belafonte’s worthy causes – similar advice might have been heeded by the filmmakers.

This review originally appeared on Little White Lies online. Sing Your Song is in cinemas now.