1. P&O Cruises: A well-known British cruise company, P&O Cruises offers a wide range of itineraries, including cruises to Europe, the Mediterranean, the Caribbean, and Asia.
2. Cunard: Another British cruise line with a long history, Cunard is known for its luxurious and elegant cruises. It offers itineraries to destinations such as the British Isles, Europe, the Caribbean, and North America.
3. Fred. Olsen Cruise Lines: A family-run British cruise company, Fred. Olsen offers a variety of cruises to destinations such as Europe, the Mediterranean, the Caribbean, and the Canary Islands.
4. Saga Cruises: A British cruise line catering to the over-50s, Saga Cruises offers itineraries to a range of destinations, including Europe, the Mediterranean, the Caribbean, and Asia.
5. Marella Cruises: Formerly Thomson Cruises, Marella Cruises is a British cruise line offering affordable and family-friendly cruises to destinations such as Europe, the Mediterranean, the Caribbean, and the Canary Islands.
6. Princess Cruises: While Princess Cruises is not specifically a UK-based company, it offers cruises from Southampton, UK, and caters to a large British audience.
These cruise companies are known for their high standards of service, comfort, and entertainment, making them popular choices for UK travelers looking for a memorable sea cruise.