Countryfile marks the 100th anniversary of Roald Dahl's birth by discovering his passion for the great outdoors and how it inspired his writing. John Craven explores Great Missenden, the village where Dahl lived for much of his life. He meets the children's author Piers Torday, who is inspired by both the countryside and by Dahl himself. There is also a look back through the Countryfile archive to the times we have met others inspired by the beautiful countryside, from underwater painters to graffiti artists. Matt Baker has more news on how viewers can take part in the Countryfile Ramble for BBC Children in Need. Last year, thousands of Countryfile viewers took part, helping to raise over ú850,000 and transforming the lives of some of Britain's most disadvantaged youngsters. With a fortnight to go until the 40th-anniversary edition of the legendary One Man and His Dog sheepdog trialling competition, Adam Henson meets the English and Scottish teams hoping to win the trophy.