The Dig is actually not a very earthy film, though there is intelligence and sensitivity and a good deal of English restraint and English charm, thoroughly embodied by the fine leading performers Carey Mulligan and Ralph Fiennes. But the passions mostly stay buried, and the movie is disconcertingly structured in such a way that we are first asked to invest in these two intriguingly complex personalities, but then – just when their emotions might get disinterred – the focus shifts to a younger pair with more obvious romantic potential, played by Johnny Flynn and Lily James. Mulligan and Fiennes look like two characters who have been written out of their own soap opera. This doesn’t stop The Dig being engaging, and with a beautiful sense of landscape.

It is based on the true story of the sensational Sutton Hoo excavation in Suffolk on the eve of the second world war; an Anglo-Saxon burial ship was found by the self-taught working-class archaeologist Basil Brown, whose historic discovery the academic establishment instantly tried to appropriate, without credit. He had been hired by the local landowner and widow Edith Pretty, who had long nursed an instinct that there was something in the “mounds” on her property. The movie is vigorously adapted by screenwriter Moira Buffini from the 2007 novel by journalist and author John Preston – whose aunt Margaret Piggott was involved in the dig.

Ralph Fiennes plays Brown, a tough, self-reliant man of few words and an outdoor tan, who does a fair bit of pipe-filling, pipe-smoking and pipe-biting. Fiennes plays him as someone who knows his worth, and he insists on getting two pounds a week from Mrs Pretty for his work and for his lifetime’s knowledge. Mulligan is Edith Pretty: intelligent, beautiful, lonely and mysteriously moved by what Brown is uncovering and by Brown’s own quietly messianic sense of purpose. But then the grand folk from London arrive, intent on taking possession of their precious discovery: Ken Stott is on great form as the pompous British Museum archaeologist Charles Phillips, his face as fierce and red as a toby jug. But along with Phillips is the mousy scholar Stuart Piggott (Ben Chaplin), a dull fellow who is failing to satisfy his young wife Margaret (Lily James) emotionally. And she is attracted to Edith’s (fictional) cousin Rory (Johnny Flynn).

Of course, the idea of digging up the past and dredging up what has been emotionally buried in one’s heart saturates the entire film. A Suffolk local takes a dim view of Edith’s encouragement of Brown and remarks that he “should leave Mrs Pretty’s mounds alone!” That’s the Finbarr Saunders school of metaphor.

But actually, in that vulgar figurative sense, he pretty much does leave Mrs Pretty’s mounds alone. Her tentative offer of dinner is complicated by the fact that Basil is married to a woman called May, shrewdly played by Monica Dolan, and there is also a secret sadness and vulnerability in Edith’s own heart that would appear to preclude any such developments, though Mrs Pretty’s young son Robert (Archie Barnes) might well be seeing Basil as a father figure.

This movie has Englishness right through it like a stick of rock, a vigorous sense of place and period, though it’s in the vein of hardback/tasteful cinema that’s a bit of a Brit movie cliche. Carey Mulligan gets the traditional hat-and-coat walk through the busy wartime London streets that was awarded to Gemma Arterton in Their Finest and Keira Knightley in The Imitation Game. The story itself is rooted in the robust literary tradition of LP Hartley, Bruce Chatwin, Graham Swift and Ian McEwan – with some Larkinian musing at the end about what will survive of us in a thousand years. Margaret tells Rory that in their case, it will the metal wheels in his watch and perhaps some fragments of their china tea mugs. No nonsense about love.

The first act about Edith and Basil is arresting and the discovery scene is great – but where will their relationship go? The second act gives us a young love story with much less depth. But maybe that is the point. Edith and Basil have their moment and it is destined to be buried by the newcomers and the vast obliterative forces of history.

• The Dig is released on Netflix on 29 January.