Earthquakes in London by Mike Bartlett at Cambridge Arts Theatre until Saturday, November 12.

Earthquakes in London by Mike Bartlett at Cambridge Arts Theatre until Saturday, November 12.

A PLAY two and a half hours long about climate change. You'd pay the price of the ticket to avoid it - right?

Well actually, much of the first half - an hour and a half but it went quickly - is charming, entertaining and lively. The staging is ingenious and the choreography (by Scott Ambler) is jolly and uplifting. I loved the girl students' party and the pram scene.

You are on the receiving end of "a message". It was reminiscent of the agitprop theatre of the 1970s and 1980s, but there was a lot more lovely sugar on the pill. It is a brilliant idea to tell the story through three sisters, a government minister, an expectant mother and a teenage student - and the men in their lives.

However, the second half creaks. In parts, it is as excruciating as fingernails on a blackboard, embarrassingly bad.

Though there are authoritative performances from Tracy-Ann Oberman, Maggie McCourt, Helen Cripps and Paul Shelley, though Leah Whitaker offers the vulnerability of the pregnant woman and Lucy Phelps the fragility of the teenager, too many others are wooden, not in the moment - just delivering lines.

Some of the writing seems to have come out of the sixth form and lends itself to performances that match. Some of it is so derivative that it could go one step further and become a parody, which might work better, a bit of panto here, a bit of Star Trek, there, a hint of Dr Who, Life on Mars.

As for the message, I have to admit bias. Is climate change a real problem? In the year 999, the medievals thought the world would end when they reached the year 1000. In 1999, some people thought at the dawn of the new millennium all the computers would stop. When James Joyce was a boy he had to listen to sermons about Hell and damnation. Hell was a real place we were all in danger of going to. The play reminded me of all that.

The actors deserve better. Kurt Egyiawan gives a fine and impassioned speech about children dying in Africa. It is visceral. Yes, we should all hang our heads in shame - but they are not dying because we get on aeroplanes or eat in French restaurants. They are dying because we don't spend our money on irrigation systems and efficient farming. They are not dying because the world may warm up at some distant time in the future. They are dying - right now because of dirty water - right now. That's what we ought to get steamed up about.

Meanwhile, back at Cambridge Arts Theatre, most of the play was fun - it was fast paced, it had moments of humour and I suspect, evoked debate for most of the audience for most of the way home