Today’s figures from Wrap represent the first time since records began that the number of single-use carrier bags being handed out has gone up instead of down.

Five percent more bags were given out in the course of last year than were used in the 12 months between June 2009 and May 2010. The government is not impressed and may now resort to legislation to get the numbers moving the right way again.

“This isn’t good enough,” thundered recycling minister Lord Henley. “Retailers need to take responsibility and lift their game to cut down on the number of single-use carrier bags they hand out.

“If results do not improve, we will consider additional measures to make this happen, including legislation.”

The laid-back line taken by the British Retail Consortium is that a 40% reduction since 2006 represents good progress and critics shouldn’t get too hung up on the most recent increase. You could sum up the body’s position as ‘Chill out, man’.

“In the face of sales growth it was inevitable that year-on-year reductions would be hard to maintain and the overall numbers remain the sort of result other environmental campaigns can only dream of,” said BRC environmental chief Bob Gordon.

However, after a couple of years of minimal growth for many top retailers, much of that driven by price increases, it seems odd to blame higher bag usage on surging volumes. Gordon’s faintly patronising tone in saying that people should get over their “obsession” with carrier bags also does him few favours.

Rightly, he notes there are “more significant environmental issues” in play than bags. But losing focus on such an eminently winnable battle would send all the wrong messages.

Ironically, the argument in favour of legislation is made most eloquently by a retailer. Marks & Spencer has cut bag use by 80% over the same period – in large part thanks to its 5p a bag charge, which has raised £4m for environmental causes over the years. The BRC may not like it, but the numbers show that charging does work.