The film's name Archipelago, is quite rich, whilst it summons the image of the Isles of Scilly, where the film is set, it also captures this sense of distance between the characters in the film, who are nonetheless part of the same family identity. Cynthia loves her brother Edward deeply, but is unable to express this other than through snide remarks, passive aggressive behaviour, and tantrums. Edward is at a quarter-life crisis, limply compassionate and full of weltschmerz, fashioned after Prince Myshkin, the "idiot" of Dostoevesky's eponymous story.
I also, haha, perhaps somewhat fancifully, like to think of Lyonesse in relation to this film, a kingdom that legendarily connected the Scilly Isles to Cornwall, and then sank into the sea. The Scilly Isles themselves are believed in Roman times to have been one island, named Ennor. Something happened and the connection to the mainland, and of the whole, disintegrated. This is much like what appears to have happened to the family in the film (it's hinted that a childhood visit to the Isles was much more light-hearted).
The film could be regarded as not much of a progression for Joanna Hogg. Both Archipelago and her cinema debut Unrelated (2007) concern upper middle class families on holiday in beautiful locations, the status of trapped outsiders, and feature the motif of an absent character continuously at the end of a telephone. However I think there's something genuinely different about Archipelago, the characters are definitely more sympathetic, and the family dynamic very different (although, such is the shock of actually seeing tangible upper middle class characters on screen that, full of schadenfreude, many British class warriors will make a bee-line for the rotten tomatoes).
The location shooting is somewhat of a kindness from the director to those of us who are so used to seeing British social realist dramas played out against bleak and unforgiving landscapes (Morvern Callar being a notable exception). There are passages in the film where Hogg lets the eye rest on pure landscape photography.
The only real happiness in the film occurs after a cathartic harangue from one character produces a genuine smile from Cynthia, who sees the healing in the foulness. This is symptomatic of a particularly British emotional constipation that is in dire need of mend.
Despite the emotional problems of the family, there are moments of genuine hilarity in the film that lightened my mood, the best being what is basically a comedy of manners sketch in a posh restaurant.
On a personal level I think I will be haunted by Tom Hiddleston's performance as Edward, too sensitive for this world, a sad and noble man, who lacks any expression of passion, and misplaces his affection. All the more remarkable given his quite opposite performance as a shallow, obnoxious and cowardly youth in Unrelated.