Lib Dem conference: G4S apology to gay rights activists
G4S has been forced to apologise to gay rights activists at the Lib Dem conference who accused the security giant of trying to stifle free speech.
The firm has been hired to conduct airport-style security checks at the Glasgow conference venue.
But its staff have also been checking for potentially offensive campaign material, it has emerged.
The policy came to light when members of the Lib Dems' LGBT+ group were quizzed by guards on Tuesday morning.
One member of the lesbian, gay, bi-sexual and transgender group, Sarah Brown, told BBC News: "We took one of our banners out to a fringe meeting last night, outside the secure zone.
"Bringing it back in this morning, (Tuesday) they wanted to unpack it. Not to see if it was any kind of threat, but to see what it said.
"They noticed it was completely innocuous - but they are there to provide physical security and it's certainly not G4S's business what is said inside a political conference and what sort of material we have on our stall."
Security has been stepped up considerably at Lib Dem conferences since they became a party of government in 2010.
The banner, which had "LGBT+ Liberal Democrats" written on it alongside a rainbow-coloured party logo, was handed back to the group.
But the incident left the campaigners, who are regular visitors to the party's annual conference and have a stall in the exhibition hall, angry about what they saw as an infringement of their civil liberties.
"It's the principle. Under what circumstances would they have rejected it?," Miss Brown told BBC News.
"What would have happened if they had decided they didn't like the look of it? They are not members of this party. They are not supposed to be in a position of controlling what members of a party say at this conference."
The group complained to the party's Federal Conference Committee (FCC), which spoke to G4S bosses at the Scottish Exhibition Centre venue about the incident.
FCC member Gareth Epps said it was an "outrageous" attempt by the security company to monitor free speech.
"We have had a number of problems with security here," he told BBC News.
"It's a clash of cultures between organisations. Between their rather authoritarian organisation and more than 2,000 Liberal Democrats."
He said the G4S security team had agreed to "wind their neck in" following the incident.
A G4S spokesman said: "We routinely make sure that banners and flyers coming into the events we secure do not contain any content that might cause offence to others.
"On this occasion we did examine a banner which was inside a bag and it was quickly permitted through security. We apologise if any delegates were upset by our actions."