Jeremy Clarkson tells The One Show viewers that strikers should be shot YouTube

Jeremy Clarkson prompted more than 30,000 complaints when he said on BBC1's The One Show that striking public sector workers should be shot. But media regulator Ofcom has cleared the programme of breaching broadcasting regulations, saying viewers should be familiar with the Top Gear presenter's "provocative and outspoken nature".

Clarkson provoked widespread outrage with his appearance on the teatime show on 30 November last year.

It led to nearly 32,000 complaints to the BBC and almost 800 to Ofcom which announced in December it would investigate the programme to see whether it broke rules on taste and decency.

Ofcom outlined the reasoning behind its decision in a letter to trade union Unison, which had lodged a complaint with the regulator.

Ofcom director Christopher Woolard said Clarkson's "provocative and outspoken nature" had been referred to in his introduction on the show "with light-hearted irony".

"Consequently, the editorial nature of the programme as a whole would have prepared viewers for the type of comments Jeremy Clarkson would be likely to make," said Woolard in a four-page letter to Unison.

Woolard said Clarkson's comments were not overly offensive in light of a general expectation of Clarkson's behaviour by viewers given his "well-established public persona".

"The audience for this edition of The One Show would have expected Jeremy Clarkson to make potentially controversial or offensive statements," said Woolard.

He added that it was "clear to most viewers that his comments were not an expression of seriously held beliefs or views that should be literally interpreted".

Woolard also said that The One Show co-presenter Alex Jones made a "wide-ranging apology" at the end of the show.

A Unison spokesperson said: "As Ofcom acknowledges, a lot of people – including many Unison members working in the public sector – were outraged by Jeremy Clarkson's comments. We felt it was important to make their voices heard."

• To contact the MediaGuardian news desk email editor@mediaguardian.co.uk or phone 020 3353 3857. For all other inquiries please call the main Guardian switchboard on 020 3353 2000. If you are writing a comment for publication, please mark clearly "for publication".

• To get the latest media news to your desktop or mobile, follow MediaGuardian on Twitter and Facebook.