The Thames: Britain's Great River with Tony Robinson

Tony watches a tunneling machine being transported up the river into central London, and discovers plans to build a new tunnel under the Thames to take pressure off the crossing at Dartford. He also makes a late-night visit to New Covent Garden Market, and meets a Paralympian in training at Marlow Rowing Club.

The actor and presenter starts his journey heading up the estuary to Southend Pier, where as a young man he'd drive to with friends. But the pier was original conceived in Victorian times to attract day-trippers from London - and tempt them away from nearby Margate. It's now the longest pleasure pier in the world and, as Tony discovers when he lends a hand replacing a girder, it requires a lot of maintenance.

The actor and presenter starts the latest leg of his journey in Beckton. There he discovers how a new super-sewer is being built to help stop overflow from London's existing system ending up in the Thames. After a hair-rising cage ride down into the tunnel, Tony Robinson meets the engineer in charge of the project who explains how it will work.

The actor and presenter starts his journey in Richmond upon Thames, at Hampton Court Palace. This 1,000-room residence was King Henry VIII's favourite. Tony begins his tour by the Thames right where the loos would have been. It's also where the royals would have arrived by barge, and where merchants from as far away as Venice would have sold their fancy fabrics.

London City Airport, right in the middle of the capital, is built on an island in the Thames itself, creating unique hurdles for the people who work there. Tony Robinson finds out more about those challenges as he meets a pilot, joins the airfield operations team, and takes part in a drill with the airport's firefighters.