One stunned official said: “We could not believe it. It was just instructions to fold some paper and some waffle about butterflies causing climate change. Not what you would normally expect from the chief executive.

“We are all under more pressure than ever, our jobs are being regraded and we just don’t have time for this nonsense.”

A second email, two hours later, finished the step-by-step instructions asking staff if they enjoyed the ‘process of change’.

Then a third, after lunch, explained the council wanted to recruit a new breed of bureaucrat called ‘change agents’ and ‘change specialists’ to run the city’s controversial Business Transformation programme which aims to save the council £1 billion over ten years through modernisation of services.

The would-be recruits are invited to bring their butterflies to an information day on July 29 to find out more about the positions.

A Birmingham City Council spokesman explained: “In order to generate interest in this programme and specifically to attract employees to apply, a conscious decision was taken to launch a very different recruitment campaign.

“The approach that was chosen, started with a couple of ‘teaser’ emails with the intention to get people talking and create a little excitement, even controversy, before fuller information was provided as part of a third and final email which invites employees to attend an information day.”

But things took a twist when Mr Hughes, after reflection, sent a fourth email distancing himself from the stunt.

He said: “Occasionally enthusiasm for an idea goes beyond what I would myself do.  The promoters of the project came up with an idea that worked in the sense it got people talking, but might have been a bit too wacky.  If I’d known earlier what they had planned I’d have advised them to do it differently.

“However, I admire their initiative, and I’d still encourage all of you to think out of the box for better ways of improving the lives of people in Birmingham.”