There currently is one option to travel by night train from London (United Kingdom) to Penzance (United Kingdom), taking approximately 8 hours: Namely the Night Riviera Sleeper WB operated by Great Western Railway.
Great Western Railway (GWR) operates the Night Riviera, a sleeper train running six days a week between London Paddington and Penzance.
The Night Riviera offers airline-style seats and cabins. Seats are complimentary and can be booked like a regular ticket. Cabins require a separate reservation and are popular, so early booking is recommended. Cabin guests enjoy complimentary light breakfast on board.
Sleeper cabins come in two types: single cabins for one person and twin cabins for two people. All cabins are comfortably equipped with a sink with tabletop and waste bin, UK plug sockets and USB points, a wardrobe, and storage space under the bottom bunk. The bottom bunk converts into a sofa for daytime relaxation. Complimentary light breakfast is delivered to your cabin.
Showers are available at Paddington, Penzance and Truro, but only for passengers who have booked cabins.
Cats, dogs and other domestic pets are welcome on board. Up to two pets can travel in your cabin without an additional pet fare, though a cleaning fee per cabin applies. Dogs must be kept on a suitable lead, and other pets must travel in a rigid carrier. Pets must remain on the cabin floor and are not permitted to sleep on beds. Only recognised assistance dogs are allowed in the on-board lounge, and pets should not be exercised in corridors or aisles.