TV Guide BBC Four Wednesday

Michael Portillo stops in Wolverhampton, where he finds out about the impact of Enoch Powell's 1968 speech. He also visits Kingsford Country Park on the outskirts of Kidderminster, investigates pigeon-racing in Worcester, and eventually looks into Cheltenham's jazz festival

The former rugby player and his wife Maureen set out on a new adventure to explore some of Wales's most beautiful places. They begin in Machynlleth, where Gareth fulfils a boyhood dream of driving a steam train. Maureen's keen too and takes charge as they wind through the stunning Dyfi Valley. However, she's less eager as they visit a centre for endangered birds of prey and has to tackle her phobia when they meet some magnificent new feathered friends

Brian explores the enigma of time, a phenomenon that is taken for granted but which, as far as physicists are concerned, is one of the biggest mysteries in the universe. He recalls highlights from his TV series that touch upon different sides of this physics conundrum, from breaking the sound barrier in a Eurofighter in order to see two sunsets in one day, to witnessing one of the oldest animal life cycles on Earth on a remote beach in Costa Rica

Bruce Parry lives with the Akie people of Tanzania, one of the last groups of hunter-gatherers to live on the African savannah. They are very cheerful, but their way of life is under threat from diminishing territory and big-game hunters

Sir Derek Jacobi reflects on the 1997 drama, Breaking The Code, which saw him in the role of mathematical genius Alan Turing, who cracked the Enigma code and helped bring the Second World War to an end. He discusses the pressures involved in playing such a significant and complex individual. Jacobi also recalls how the project started as a play that, to his surprise, became a hit in London's West End and on Broadway

Drama tracing the real-life story of mathematical genius Alan Turing, who was instrumental in cracking the Enigma code during World War Two but found the pressure of his work and homosexuality too great to bear. Starring Derek Jacobi, Prunella Scales and Richard Johnson. Part of Hidden Lives Week

Historian Sam Willis charts how Edward I turned the castle into an instrument of colonisation. He spent a large amount of money on subduing the Welsh and built fearsome fortresses in Caernarfon, Gwynedd and Beaumaris, which were used to impose England's rule on the country. However, when the king's attention turned to Scotland, his plans didn't go as expected