Free speech advocates says Tonkin + Taylor doesn't need to apologise for an employee allegedly heckling the Deputy Prime Minister. 

A man appearing to be wearing a company lanyard yelled and swore at Winston Peters after an announcement on rail funding at Wellington's train station.

The engineering firm has since apologised and says it'll investigate.

The Free Speech Union's Nick Hanne says there's a line between work and personal expression. 

"This is an issue that isn't actually directly related to the work that their employee does - and of course to what they do as a company - so it just seems like complete over-reach."

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