BBC Four HD SkyTV

2/2. By the late 1880s, the buffalo teeter on the brink of extinction. [S] [HD]

7/15. Michael Portillo continues his railway exploration of the postwar Britain of his youth on a journey from London to Cambridge, starting at South Bank. [S,AD] [HD]

1/5. Explorer Paul Rose sets off on the walk of a lifetime - 630 miles of the South West Coast Path, discovering wildlife, wild traditions and wild adventure along the way. [S] [HD]

3/6. Series about the creatures that live in China's most beautiful landscapes. This episode looks at the remote Tibetan Plateau, home to chiru antelopes, wild yaks and bears. [S,AD,SL] [HD]

Programmes start at 7.00pm. [HD]

Programmes start at 7.00pm. [HD]

8/15. Michael Portillo ventures deep underground onto London's newest railway: the Elizabeth Line. He travels across London before transferring to the Epping Ongar Heritage Railway. [S,AD] [HD]

2/5. Five-part series in which explorer Paul Rose walks the South West Coast Path. Here, he explores the rugged north Cornish coast and takes a grand tour of Tintagel Castle. [S] [HD]

2/4. Brian Cox looks at our attempts to discover whether we are alone in the universe. [S,AD] [HD]

2/6. Explorer Bruce Parry travels to the frozen tundra of Northern Siberia, spending a month with a brigade of Nenet reindeer herders during their winter migration. [S,AD]

5/6. Seminal 1982 spy drama series. Smiley is hot on the trail leading to Karla but must make the ultimate sacrifice - cutting off his wife Ann. [S]

6/6. Seminal 1980s spy drama series. The final confrontation between Smiley and Karla takes place. But in this game there are no victors, only losers. [S]