While Charles Darwin was writing his last book, he wanted to know if worms could hear. He observed them in his garden, and he experimented with them in glass cases in his study. As usual, his children were helping him. So he asked his son Frank to play his bassoon to the research sample. Frank played and played but the worms kept on wriggling, just as they always did. Darwin concluded from this that they must, therefore, be deaf.

This is just one instance of the endearing qualities of one of the greatest 19th-century scientists, whose home, Down House, has now been reopened after a year’s sensitive refurbishment by English Heritage.

It’s a large and comfortable house in the village of Downe, near Bromley in Kent. Darwin lived there from 1842 to 1882; it is where he wrote his great works and anxiously sat on his revolutionary theory of evolution until he finally published it in 1859. After his death, his widow Emma and some of his seven surviving children lived at the house. It then became a school until it opened as a museum in 1929.

By the 1990s, the house, grounds and exhibition were in urgent need of an overhaul. With the help of the National Lottery and the Wellcome Trust, English Heritage has been able to spend more than pound;2 million on restoration.

So far the money looks well-spent. The downstairs rooms have been refurbished to show what a visitor in the 1870s (the Darwins had many of these, apparently) would have found if he managed to get past the formidable butler, Parslow. In Darwin’s study he would have seen the large armchair with iron legs and castors where, on a board stretched between the arms, Darwin wrote On the Origin of Species. There is also a tiny curtained sickroom in the corner where Darwin weighed himself daily and vomited frequently. Real illness or hypochondria?

In the billiards room, Darwin would often be found playing the game with Parslow - he found it soothing, saying it helped to drive out “the horrid species from my head”. In the drawing room, Darwin’s wife would play the piano. This is a pleasant, bright family room with a verandah and music stands and comfortable chairs where Emma would read Victorian novels to her husband as an afternoon relaxation - a key part of his metronomically regular but highly productive domestic routine. (Darwin wrote every day but in short bursts. And he played a lot - in a very un-Victorian way - with his children.) Upstairs is quite different. No attempt has been made to reconstruct the numerous bedrooms, although you can still see where the children carved their names inside a cupboard in their schoolroom. Instead there is a series of themed exhibition rooms with hands-on activities.

A whole room is dedicated to Darwin’s astonishing five-year voyage on HMS Beagle, with videos and a vivid impression of life at sea on what was, by modern standards, a minuscule ship. You can see the enormous and fascinating log he kept on the expedition. In another room, an encouraging mini-biography shows that Darwin failed as a medical student and only came into his own in his mid-twenties.

His central theory of natural selection is simply and imaginatively explained in a “Discover Darwinism” room - the controversies which followed his reluctant publication of On the Origin of Species are well-documented.

The gardens are where he experimented with plants, spent hours tracking the flight of bumble bees with the children and where he took his quarter-mile constitutional every day.

School visits to Down House will take place on Tuesdays (all day) or Wednesdays and Thursdays (lunchtimes only) and must be booked. ‘Charles Darwin: his life journeys and discoveries’ by Caroline Overy is the latest in English Heritage’s Education on Site series of publications. It is available from Kate Whelan at English Heritage, tel: 0171 973 3485