Watch Titanic The Mission online: Episode 4 Smoking Room and The Third Class Cabin

The engineers focus on the interiors, fixtures and fittings of the Titanic, and rediscover the lost skills of British craftsmen and women by re-creating the centre section of the most expensive room on board the ship - the gentlemen's first-class smoking room. They also build the more humble third-class cabin, which still represented working-class luxury in its day, and unveil both replicas in an exhibition at Belfast's biggest museum, with surprising results.

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