“The whole world's in a terrible state of chassis,” says Captain Jack Boyle more than once during Sean O'Casey's great play, set in 1922 and the second of his Dublin trilogy, bookended by The Shadow of a Gunman (1923) and The Plough and the Stars (1926). It was first performed at the Abbey Theatre in Dublin in 1924, when Ireland - only recently free of the yoke of empire – was tearing itself apart over the 1921 Anglo-Irish Treaty, which established the 26-county Free State, later the Republic.

Don't be misled by the mini-history lesson with which Trevor Nunn's belated London stage premiere of The Lion in Winter begins, a sequence of dates, facts and maps that scroll up a decoratively appointed screen and threaten to turn the sumptuous Haymarket Theatre (Nunn's home now across four productions) into an upscale schoolroom.

Nearly 20 years have whizzed by since Jonathan Harvey, then a 24-year-old comprehensive school teacher, wrote a play in the school holidays – and caused a stir. That play was Beautiful Thing, dealing with the then (and now?) contentious issue of two 16-year-old schoolboys, next-flat neighbours in the high-rise south-east London council estate of Thamesmead, who fall in love – and overcome prejudices and obstacles, not least their own self-realisation.

Many dramatists have taken their turn putting faces to Thoreau’s lives of “quiet desperation”. But the challenge in what Thoreau goes on to conclude – that it is therefore a mark of wisdom and the wise to avoid acts of desperation – has been taken up by far fewer. Salt, Root and Roe sees Tim Price transform an act of violence from one of apparently senseless desperation to one of humane intelligence and generosity.

Some plays are so weird they defy description. Well, almost. One of these must surely be the late James Saunders’s deeply absurdist play, whose first outing in 1963 launched the career of the young Michael Caine. Soon after, its author won a promising playwright award. The current revival, part of the Orange Tree’s 40th-birthday season, gives us a chance to look again at a writer whose innovative work has been consistently promoted by Sam Walters, artistic director at this address.

If you didn't know Frederico García Lorca's Yerma before this show, you probably wouldn't be any better informed after watching Natalie Abrahami's engaging but flawed production. In “a new version by Anthony Weigh”, as it says on the programme cover, a backstory of the childless couple Yerma and Juan is interpolated in the Spanish playwright's 1934 "Tragic Poem in Three Acts and Six Scenes” and its chorus has been excised in a much-reduced cast.

Family occasions can be fraught affairs, as playwrights from Harold Pinter to Alan Ayckbourn have convincingly proved, but the mother of all family meltdown dramas must be Thomas Vinterberg’s Danish Festen, a Dogme 95 film made in 1998. Soon after, this was turned into a stage play by Vinterberg and Mogens Rukov, which had an outstanding success in David Eldridge’s version here in 2004. Now a Romanian theatre company, Nottara, from Bucharest, bring their version to London.

First come the strip-lit corridors, the stained breeze blocks, the locked doors; later there are restraints, drugs, needles. The time is out of joint, and we are all imprisoned in a nightmare of confusion, paranoia, guilt and despair. Who are the mad? Who the sane? In Ian Rickson’s thrilling production of Shakespeare’s great tragedy, it’s often frighteningly unclear.

Is this the year that G&S became definitively chic again? The slow-burn effect of ENO's "Miller Mikado" and Mike Leigh's Topsy-Turvy now results in numerous fringe benefits. Sasha Regan's all-male Union Theatre regime has delivered its best yet - Iolanthe at Wilton's Music Hall, the most touching and funny show I've seen over the last 11 months - and now Charles Court Opera gives us more witty operetta-in-close-up with a cast of nine backed up by two pianos.

Journalism is often used to create compelling true-life plays. This drama, written by award-winning actor Nichola McAuliffe, has both a journalistic writing style and a journalist - actually the playwright’s husband - as a central character in a tale about rough justice set in Pakistan. Having wowed audiences in Edinburgh and New York, what kind of impression does this piece, which opened in London last night, make in the metropolis?