The earliest film kiss held by the BFI National Archive is this stolen smooch aboard a steam train, intended as a comic filler sequence to play as part of the ‘phantom ride’ films popular in Victorian cinema. G. A. Smith's 1899 film shows a train going into a dark tunnel, revealing a couple in a railway carriage taking the opportunity to steal a kiss. As the train apparently emerges into the light the couple move apart in a guilty fashion, and although scarcely enough to make your Victorian grandmother blush, it gives the scene its slight frisson of naughtiness.
But Smith's Kiss in the Tunnel is also one of the world's most important early films because it is one of the first to edit together several related shots.
Exhibitors were recommended that it be shown, to add humour, between a phantom ride of a train going into, then coming out of, a tunnel.
The couple are played by George Albert Smith and his actress wife Laura Bayley, the railway film is Hepworth's View from an Engine Front - Train Leaving Tunnel (1899)