When's the last time you encountered a play with a hissable anti-hero and a young heroine who radiates charity, decency, and all things good? Those polarities are on full-throttle view in The Stepmother, the all-but-unknown Githa Sowerby play from 1924 that makes up in its vigorous appeal to the jugular what it may lack in dimension and subtlety (Chekhov this ain't.) And if the opening night is any gauge, Sowerby's tale of a young wife and her unctuous, much older rapscallion of a husband has a demonstrable capacity for evoking responses from the crowd.

There’s nothing novel about novel-adaptations on stage. We’ve seen every classic from Pride and Prejudice to Tess of the D’Urbervilles, The Woman in White (and The Woman in Black) get the full theatrical treatment, and I’m not sure any have ended up the better for it. The power of a tale is in the telling, and unmoored from the delicate narrative handling of an Austen or a Dickens things can go horribly awry.

Last weekend it was the 50th anniversary of an important event in postwar Welsh history. In early February 1963 the Welsh Language Society – Cymdeithas yr Iaith Gymraeg – protested for the first time about the right of Welsh speakers to live their lives in Welsh. At Pont Trefechan in Aberystwyth 500 people gathered on Saturday to mark the event and the same number came back on Sunday to Y Bont (The Bridge), a commemorative outdoor play devised by the Welsh-language National Theatre, Theatr Genedlaethol Cymru.

A little man takes on Authority and fails. A little man dons a colourful uniform, complete with boots and spiked helmet, and he becomes Authority. Carl Zuckmayer wrote Der Hauptmann von Köpenick in 1931, two years before Hitler came to power.

Plays about plays are often touched by theatrical magic. This is certainly the case with Timberlake Wertenbaker’s masterpiece, first staged in 1988, and now revived by the same director, Max Stafford-Clark, who originally eased it into the world. And, just as a quarter of a century ago the play felt like a protest against the moronic anti-arts prejudices of the Thatcher gang, so today it once again asserts the power of theatre as against the crippled vision of Arts Council cuts.

The walls of the staircase to the Finborough Theatre off the Earls Court Road are lined with framed awards. Downstairs for the umpteenth time, the café/restaurant has gone bust. But no other London fringe theatre has achieved such stellar success as this tiny pub theatre under the helm of its restless, irrepressible artistic director Neil McPherson, who has made a cottage industry out of discovering forgotten gems.

Feast aims high. Very, very high. Steered by experienced and much-lauded director Rufus Norris, five playwrights and one choreographer seek to make a fusion of physical theatre, dance, onstage music, straight drama, abstract poetic dialogue, projected animation and knockabout comedy to tell no less a story than 350 years of the history of the Yoruba people of west Africa. It spans four continents through recurring manifestations of a group of their “Orishas”, or gods, a series of meals, and an ongoing quest for eggs. Yeah, that old chestnut.

This production of Old Times is a big deal. It’s the first of Harold Pinter’s plays to be performed in the theatre renamed after him; it marks the reunion of director Ian Rickson and Kristin Scott Thomas, after their exhilarating Betrayal; and it feels like a seminal reading, involving a casting conceit that makes a rich work even richer, even more mesmerising.

There is never a dull moment in this three-hour historical epic, even if it is not always clear what is going on. Directed by Gregory Doran, of the RSC, Anjin follows the 17th-century story of William Adams, the first Englishman to land in Japan. The production has lines in English and Japanese, with surtitles above the stage and on either side, but it is sometimes difficult to read the words and watch the characters, especially for audience members in the middle of the stalls.

A wise man once said of Simon Gray's plays - and he wrote a lot of them - that they often have a lot of talk and very little action. And so it is with his 1981 tragi-comedy, set in the staff room of a language school for foreign students in Cambridge.