Seat for passengers of a vehicle, in particular a railway vehicle, comprising: - a seat connected to a backrest, which has a front side facing the seat and an opposite rear side, - a shelf, comprising a tray with an upper face, the shelf being mounted on the rear face of the backrest by means of a hinge defining a hinge axis, such that the tray is rotatable relative to the backrest about the hinge axis between a stowed position in which the upper face of the tray faces the rear face of the backrest, and an open position, in which the upper face of the tray faces upwards, the tray defining a length, measured radially to the hinge axis between an inner edge and an outer edge of the tray, the top surface of the tray having a retaining relief, which defines a depth (P74, P76) measured orthogonally to the top surface and which is configured to prevent objects placed on the top surface of the tray from sliding off, wherein the top face of the tray comprises an inner region and a complementary peripheral region, the inner region extending from the inner edge of the tray over a distance less than 80% of the length of the tray, preferably less than 50%, and in which the retaining relief is provided on the inner region of the plate, while the peripheral region is substantially smooth and free of retaining relief, characterised in that the depth (P74, P76) of the retaining relief decreases as the relief is removed from the hinge axis. - a seat connected to a backrest, which has a front side facing the seat and an opposite rear side, - a shelf, comprising a tray with an upper face, the shelf being mounted on the rear face of the backrest by means of a hinge defining a hinge axis, such that the tray is rotatable relative to the backrest about the hinge axis between a stowed position in which the upper face of the tray faces the rear face of the backrest, and an open position, in which the upper face of the tray faces upwards, the tray defining a length, measured radially to the hinge axis between an inner edge and an outer edge of the tray, the top surface of the tray having a retaining relief, which defines a depth (P74, P76) measured orthogonally to the top surface and which is configured to prevent objects placed on the top surface of the tray from sliding off, wherein the top face of the tray comprises an inner region and a complementary peripheral region, the inner region extending from the inner edge of the tray over a distance less than 80% of the length of the tray, preferably less than 50%, and in which the retaining relief is provided on the inner region of the plate, while the peripheral region is substantially smooth and free of retaining relief, characterised in that the depth (P74, P76) of the retaining relief decreases as the relief is removed from the hinge axis. the top surface of the tray having a retaining relief, which defines a depth (P74, P76) measured orthogonally to the top surface and which is configured to prevent objects placed on the top surface of the tray from sliding off, wherein the top face of the tray comprises an inner region and a complementary peripheral region, the inner region extending from the inner edge of the tray over a distance less than 80% of the length of the tray, preferably less than 50%, and in which the retaining relief is provided on the inner region of the plate, while the peripheral region is substantially smooth and free of retaining relief, characterised in that the depth (P74, P76) of the retaining relief decreases as the relief is removed from the hinge axis.