Educated at Winchester and Oxford, lifelong socialist, closet gay, son of a Liberal prime minister, Anthony Asquith (1902-1968) is a currently undervalued film-maker whose career began in the silent era when he studied American cinema in Hollywood and German expressionism in Berlin. The British character in its various forms fascinated him, especially the middle classes, and he found an important collaborator in Terence Rattigan. Their association lasted from 1937 to the mid-1960s, resulting in numerous crucial works, including the wartime morale-booster The Way to the Stars and that masterpiece of stiff-upper-lip repression, The Browning Version.

Just before the coming of sound Asquith made two silent classics, A Cottage on Dartmoor and Underground that put his rival Hitchcock into the shade in the way it absorbed foreign influences and experimented with new styles. Underground is an exhilarating celebration of modern city life as embodied by the London underground system, its art deco stations and the mixture of all classes it brought together for brief journeys on its elegant, fast-moving electric trains. The four central characters are all working-class: an underground porter, a shop girl in a West End department store, a seamstress and a womanising power-station engineer. Lyrical romance, observant social comedy of a kind associated with Ernst Lubitsch and tough melodrama are brought together in a movie that never patronises the working classes, probably because there are no defining social accents to be heard. Elissa Landi and Brian Aherne went on to modest Hollywood stardom. Asquith resolutely stayed at home.

The technical restoration of this film is a triumph. Neil Brand's score is excellent. The disc's additional features about the underground are of considerable interest, and there's 60 seconds' worth of the eight-year-old Asquith and his dad at a 1910 aerial display.

• This article was amended on Tuesday 2 July to correct a number of production errors.