You know that thing when you’re having a conversation with someone, but actually you’re hardly concentrating because you’re wrapped up in other thoughts about other problems – and you hope the person you’re talking to doesn’t notice; well, has it ever occurred to you that the person to whom you are talking is also not concentrating because they too are immersed in their own thoughts and daydreams? No, me neither. But that is the central tenet of Alan Ayckbourn’s 2013 play, Arrivals and Departures, his 77th, would you believe; I was going to call it his new play but I see that there’s already a 78th opening in Scarborough this summer.

This very inventive and rewarding play is set at a London railway station and, from reading the programme notes, you get the feeling Ayckbourn has always wanted to set a play in a railway station. Observing people in transit, people waiting for others to arrive, and the people who work at the station, and so on – I think this has been an ambition. For Arrivals and Departures, it’s almost as though he has taken the ideas for two separate plays – a “train station” play and a “memory, obsessed with one’s own thoughts” play, and very successfully woven the two together.

Maybe there are even traces of a third play here too – in the actual plot, which is way beyond the boundaries of your average domestic comedy. When the play starts you are a little confused as to the set-up, but you quickly realise that you are watching the preparations for a military security operation, an attempt to ambush and capture a terrorist on the train coming down from up north into London. This doesn’t feel like typical Ayckbourn territory, but then he has written about so many subjects now that I don’t think there is such a thing anymore. As the rehearsals for the ambush team progress, we meet Barry, a well-meaning but over-talkative Yorkshire traffic warden, who is the one person that has met the terrorist and would be able to recognise him in a crowd – so he is there to confirm that the guy they capture is the right one. We also meet Ez, (not Esme, as she will frequently point out) a somewhat wayward and unconventional soldier whose job it is to protect Barry, should it come to that particular crunch.

As we await the arrival of the train containing the terrorist, code name Cerastes, we see flashbacks in Ez’s mind as she recollects her childhood and the difficult relationships with her mother, and how, as a result, she finds it hard to commit to a relationship with Rob, a seemingly decent soldier type, which has its own unfortunate consequences. Her conversations with Barry get in the way of her thought processes, but his good nature starts to break down her resistance; and when the terrorist does finally appear, she successfully manages to protect Barry, although Barry is convinced they’ve got the wrong man. Here comes the interval.

I won’t tell you what happens next, but it’s absolutely not what you were expecting. Suffice to say, this is a “time” play, so expect Ayckbourn to manipulate the usual conventions to make his point. I was kind of dreading a rehash of his play “Improbable Fiction”, which was the last Ayckbourn we’d seen at the Oxford Playhouse, and which had a hilarious first act but (for us) a totally stupid, useless, surreal and not at all satisfying, second act. I needn’t have worried. Arrivals and Departures is a supremely better play, which opens up a lot of loose ends before neatly tying them all together. I do have one criticism though – the structure of the play requires a certain amount of repetition in the plot and dialogue, and I did think that this detracted a little from its overall dramatic intensity. However, there is also the fun for the audience of working out where there will be repetition and where there will be new material – you can’t always second-guess it. The plot climax definitely moves the action forwards, and is one of the most touching conclusions to a play I’ve seen in some time. To be honest, the lady on the other side of Mrs Chrisparkle sobbed her heart out.

Kim Wall plays Barry and it’s a complete star performance. I’ve told you before how I first came across Mr Wall, so I won’t bore you with that story again; however, he remains one of my favourite actors, and I wonder why he has never really hit the big time. Barry’s vocal mannerisms, the way he doesn’t like to let a silence go unfilled, his potential to be really boring, his underlying total kindness, his dignified but positive response to the cruelty of life and his complete lack of regard for his own safety, are all beautifully brought to life in Mr Wall’s performance. Equally good is Elizabeth Boag as Ez, uncomfortable, soul-searching, reserved, but with the possibility of allowing the ice in her heart to thaw. Mrs C pointed out how extraordinarily well she conveyed anger (Mrs C has a great dislike of the default position of “anger = shouting” in some productions we’ve seen). There’s a brilliant scene between Ez and Barry, where she loses her cool with him and tears an unnecessarily sharp strip off him – her gradually changing reaction as she realises what she has done is superbly conveyed.

It’s an excellent ensemble performance throughout, with the cast of eleven playing thirty roles. In the performance we saw, the role of Quentin, the leader of the security operation, was played by Peter Halpin and he was superb; a vain, self-absorbed little Hitler if ever there was one. When his operation comes to a not-entirely-satisfactory conclusion, all he can think about is himself. It’s a very clear depiction of someone who isn’t actually as good at their job as they think they are, or indeed ought to be. In all the memory scenes, I particularly enjoyed Sarah Parks as Ez’s worrisome mother, and James Powell as the young Barry, all 70s suit and ineffectual bonhomie; but all the cast give an excellent account of themselves.

I would have liked to see the other productions that are in repertory with this play, all performed by this Ayckbourn Ensemble company; namely a revival of 1992’s Time of my Life, and two one-act farces combined under the title Farcicals, which sound like an antidote to the serious themes of Arrivals and Departures. However, as Mrs C often tells me, “you can’t see everything”. The plays are on at Warwick Arts Centre this week, and then go on to Cambridge, Cheltenham, Bath, Watford and Windsor. If Arrivals and Departures is anything to go by, these audiences are in for a treat.