From the Historic England entry:
“Interiors followed a standardised plan adapted to the particular site, comprising a ground-floor ticket hall with lifts and a spiral stair down to corridors, and further stairs down to the platforms, which were usually parallel.
(Russell Square) INTERIOR: Ticket hall remodelled in the 1990s and retains no visible original features. A small area of original green tiling remains in the straight stair down to the spiral stair. Original tiling in turquoise, black and cream survives in the spiral stair and in lower passageways, including directional signage. Platform tiling was replicated in 2009, apart from the soffit banding.”