Some of the people who spoke to ITV News about alleged security breaches by G4S staff were sacked by the G4S and have tribunal cases against the company.
The man in charge of the operation, the G4S Managing Director of Global Events, Ian Horseman Sewell, rejected all their claims:
"At no point is there any evidence that dogs that have been trained to detect substances other than explosives have been used to try to detect explosives."
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Speaking after the Westminster attack, Brad Smith exclusively told ITV News that Microsoft will only hand over data when legally compelled.