For weeks, commentators have waited with bated breath for the EU referendum debate to get ugly. We may have seen the first signs during today’s justice questions in the House of Commons.

Former justice minister Jonathan Djanogly rose to his feet to ask ministers whether they would agree that up to £1.7bn-worth of income from legal services could be put at risk from a vote to leave the EU.

But before ministers could answer, an unparliamentary expression could clearly be heard from nearby.

The source of the expletive remained unknown until a point of order after questions had finished. Conservative MP Michael Fabricant admitted to using an ‘unseemly’ word ‘beginning with b and ending with cks’. He explained his behaviour was due to a ‘colleague of mine using yet another scare story about what a disaster [Brexit] would be’.

Speaker John Bercow admitted to hearing the word, but said he had considered it best to move swiftly on.