The seating was of a high backed type, unique to Class 104 & 110. First class had tubular frame seats upholstered in Dunpillo and trimmed in a blue shade of uncut moquette (with a "floral shaped" vertical stripes) and contrasting blue Vynide panels on the seat frame and back panel, and had
armrests and headrolls. There was also a blue carpet over the linoleum. Second class seating was also tubular framed and upholstered in Dunpillo but trimmed in cut and uncut maroon moquette (with a narrower fawn/buff/light brown type colour vertical pattern approx. 1" wide), and grey green Vynide panels in the seat frames and back. Headrolls were provided, but not arm rests. The floor had a green shade of linoleum.
Self coloured anodised light alloy luggage racks ran the full length of saloons, which in most cases were finished in polished veneered plywood. The first class was rose zabrano and the second class lacewood. The type of wood was identified by a small plaque inside each saloon on the vestibule walls above the archways. The exceptions were the NER sets, which had light blue formica in first class and light green in second. On all cars the window frames and panel beading were made from wood (most DMUs had alloy frames and strips). Vestibule bulkheads were formed from blockboard and veneered to match the saloons, with windows of armoured glass. The interior sliding doors were also blockboard but veneered in mahogany to match the mahogany framing in the bodyside and bulkhead windows. Standard BR bodyside windows with sliding ventilators were used, and Beclawat full-drop balance windows were fitted to the bodyside doors. Blinds were fitted to the second class windows, with curtains in the first class. Toilets were finished in primrose yellow plastic with furnishings to match.
Two S. Smiths & Sons fuel oil burning heaters were provided per car, each operating independently. One used fresh air from the outside and the other used recycled air. Ozonair filters were fitted to both systems between the air intake and the heater. The air was fed through longitudinal ducts along the bodysides and distributed at floor level. There were two feeds into the van through the partition, capable of being blanked off at the guards discretion, and another feed to near the guards seat. The drivers' cab and toilets also had feeds through the partitions. Warm air, and cool air from a grille on the front of the cab under the secondmans window, was fed into a mixing chamber which had a flap valve allowing the temperature to be controlled for de-misting and de-frosting. This was aided by an electric driven fan which blew the air to the distributing duct at the bottom of the drivers window.
There was good use made of fibreglass in the construction, for the cab roof and ceiling, front and side cab interior finishes, and alarm valve covers, which were in a dove-grey finish. It was also used for the covers over the heating ducts in vestibules, in a shade to match the anodised aluminium kickplates on the vestibule bulkheads.
Communication between the driver and guard was by electric buzzer, and there was an electric bell system that warned both driver and guard if any engine went on fire. Smith's Industrial Instruments provided the speedometer equipment, with Smith-Stone speed indicators, and a Smith-Stone distance counter on one axle of each power car. The cab controls were laid out in a manner similar to other manufacturers. The cab windows were 1/4 inch armoured glass, with Laycock pneumatic windscreen wipers, some fitted to both sides, some vehicles had one fitted to the drivers side only. Although not fitted when new on the first units, a Trico-Folberth window washer was added.
The door vestibule end of the TC and TS vehicles and the gangway ends in all vans were fitted with the same sized windows as the cabs, one either side of the gangway.
All the Eastern Region allocated vehicles were built with a luggage rack area opposite the toilet. One double seat was omitted to accommodate the rack, and the triple seat backing onto the toilet was replaced with a double.