When You Me BumBum Train took the site-specific theatre world by storm in 2004 at the Barbican with its unique concept of an audience of one in a wheelchair and a cast of hundreds, and all over again when it was presented during Olympics season at Stratford, people were blown away by the originality and audacity of both concept and execution.

Most – especially luvvyish actors – emerged into the bar at the end gasping like freshly landed fish.

This time round, the ‘passengers’ seemed less excitedly incoherent, and perhaps the adrenaline rush isn’t so strong.

It could be partly due to their frustrations in getting a £48.50 ticket – the booking system collapsed within minutes on June 21 as up to 50,000 mailing-list subscribers chased 70 places a night on the two-month run. When we rang the office with a simple query about timing and location, staff were almost tearful with stress as after three months’  intense preparation this year’s production didn’t get its health-and-safety approval until two nights after it should have opened.

BumBum Train sensibly surrounds itself with a non-disclosure policy – if you know exactly what’s going to happen in the multiple scenes through which ticket-holders are propelled, you won’t enjoy it half as much. They also ask that no-one sees it twice, even in different locations.

One of the best jokes in this year’s Edinburgh Festival Fringe came from 12-year-old comedian ‘Grace The Child‘ who said “They’re always telling me to live my dreams. But I don’t want to be naked in an exam I haven’t revised for.”  BumBum Train may not place you naked in an exam room, but it is designed to challenge your imagination and maybe face such fears.

It isn’t like giving away that the policeman does it in The Mousetrap, though, to say it feels like ‘your whole life passing before you’ and co-creator Morgan Lloyd has said it’s intended to simulate a succession of events and situations no one person could experience in a lifetime.

As you expect from the word-of-mouth hype, it is incredibly well done from the point of view of microscopically detailed authenticity in the sets, the dedication of the 300-strong amateur cast of actors and extras, and the heightened realism of the situations in which you’re placed. But although there’s some tensely-delivered topicality to keep things fresh, there’s very little naked-in-the-exam-room jeopardy – entering each space you swiftly take in the scene and what’s required of you as the centre of attention in the minute or so which follows, but nothing seemed so Kafkaesque or daunting that anyone who didn’t enjoy a bit of improvisation or had even watched a fair bit of reality television would find outside his comfort zone.

I wanted more surrealism and insanity in my carousel of fantasies.

The use of your own name is a repeating meme, and there is at least one jaw-droppingly effective usage of it which will have you wondering how on earth they manage it – but too many scenarios begin with a broadly similar welcome and being told what to do, the most intriguing situations would leave you to figure it out.

It also seems a lot shorter – we were ‘out’ barely forty minutes after the ‘ride’ began, and at Stratford – where I was a cast member – it felt more epic.   Maybe now the best end of the fun is to be a participant: the enthusiasm of the near-evangelical volunteers is undeniably infectious and I really enjoyed some of the scenes I got to play in 2012, like a doctor flipping a succession of ‘patients’ over on my hospital trolley – and finding that a much-admired actor or celebrity chef had terrible breath.

Sorry, Jamie.

The featured photograph is not a scene in the 2015 show.