The Thames: Britain’s Great River with Tony Robinson, C5, 8pm

THE eponymous actor has always been fascinated by the River Thames. He was born in London and his family have lived for three centuries. Now he is travelling the 200-mile journey from source to sea to discover what makes it one of the greatest rivers in the world. The Blackadder and Time Team veteran begins where the Thames emerges from the ground as a pure spring in a Gloucestershire field.

63 Up, STV, 9pm

IN 1964, ITV began a series entitled Up, inspired by the Jesuit motto, “give me a child until he is seven and I will give you the man”. This time, viewers have an opportunity to catch up with the people they first met 55 years ago. Over the decades, we’ve watched them grow up as they’ve completed school, got jobs, married and had children. Now they’re reaching retirement age. Among those featured is Tony, who gave up a career as a jockey and became a cabbie, and Sue, who was first on the show with her friends Jackie and Lynn.

The Planets, BBC2, 9pm

PROFESSOR Brian Cox continues his fascinating tour of our solar system, revealing that it was once home to not one, but two blue planets. Today, Mars, the fourth planet from the Sun, is an arid desert world that long ago had the same potential as Earth. Did life get a start on both and what occurred to enable one to thrive while the other dried out? Does the fact pieces of the Red Planet have been found on Earth hold any clues.

Great British Gardens: Season By Season with Carol Klein, C5, 9pm

THE host of this new series has long been one of the UK’s best loved green-fingered experts, partly thanks to 14 years on the evergreen Gardeners’ World. Now Klein visits some spectacular plots and meets the people who look after them, beginning in Sussex High Weald. Head gardener Fergus Garrett talks about how he endeavours to use the grounds as a living laboratory of horticultural experimentation, and encourage biodiversity of plant and animal species.