How much of a part do expectations play in our experience of theatre?

OK, I admit it: I was seriously dreading Peter Gynt, which opened at the National Theatre last night. With a running time of some three-and-a-half hours, the prospect of spending the evening watching this famously impenetrable - even possibly unstageable - Ibsen epic didn't fill me with happiness.

Indeed, one of the best solutions ever proposed for solving the staging difficulties of putting the play on was offered by the title character of Willy Russell's Educating Rita: "Do it on the radio", she told her teacher.

Perhaps the law of lowering one's expectations worked in this new production's favour, but I was seriously absorbed -- and even more happily, seriously entertained - by this new version written by David Hare and directed by Jonathan Kent. As I wrote in my review for LondonTheatre.co.uk: "It's by no means an easy watch, but this entirely watchable production both surprises and illuminates a play that I've previously thought was impossible to actually enjoy."

Of course, it could just be in the timing; at a time when it's not difficult to feel an existential dread about where the world is headed, it speaks directly to some of my concerns. And as someone who has also suffered from recurring depressions in my life (and is currently experiencing a return bout), the journey of the play's title character to make sense of his life and give it shape and meaning is something I seriously identify with.

(One of my all-time favourite musicals Pippin is about a similar journey, and for exactly the same reason). Even more personally, there's a scene where Peter comforts his mother on her deathbed: again, it's a scene I played out in my own life last November.

This production will not, I fear, be to everyone's taste; there were empty seats before it even started, and more after each of its two intervals. But as a show that totally defied my own expectations, inspired and moved me, it was a wonderful surprise.

The night before, I'd re-visited Jesus Christ Superstar, now transferred indoors to the Barbican Theatre after I'd seen it three times at Regent's Park Open Air Theatre, during its original runs there in 2016 and 2017 - so it also came burdened with expectations, too, but of the opposite sort to Peter Gynt.

Would it - and could it? - live up to my exalted memories of seeing it under a gradually darkening sky in the great outdoors, which only amplified its richness and moving sense of drama?

Sometimes Regent's Park can make a show feel site-specific - not least when it staged Sondheim's Into the Woods in 2010, which won the Olivier Award for best musical revival. In a programme note for this transfer of Jesus Christ Superstar, Lloyd Webber biographer Michael Coveney wrote: "In 2016 it was fascinating to see the musical with so many great outdoor scenes - the entry to Jerusalem on Palm Sunday, the betrayal in Gethsemane and the climax on Calvery -- in the first British al fresco production under a darkening sky at Regent's Park Open Air Theatre."

But even though, as I wrote in my review, "its energy feels a little more constrained - even on a stage as high and wide as this one, which can't reach to heaven itself as the outdoor version does", it's a mark of how great this production is that its energy and daring is still undiluted indoors.

Last weekend, I was back outdoors, with some 75,000 other souls, for Barbra Streisand's concert in Hyde Park. It's hardly possible for anyone to draw an audience into an intimate embrace in such a large space, but Streisand's star power and surprising vulnerability succeeded more than I could have possibly have imagined.

Some 52 years ago, Streisand last appeared in a park in a massive concert in New York that was called A Happening in Central Park (it was reportedly attended by 135,000 people and has lived on forever in a live album of the night). I was only four at the time, so alas missed it.

But I'm glad I didn't miss this 'Happening in Hyde Park', as Streisand redubbed it. Even if the concert is minutely scripted - all the lines, spoken as well as sung, are projected onto massive screens in front of the stage - her natural vivacity and still golden notes (at 77 years old) hold the audience in the palms of her hands.

It felt historic. Expectations, in this case, were irrelevant: just her being there, and us being with her, made the night.