The journalist was celebrating at a "Covid compliant" restaurant but afterwards "popped into" another venue to use the bathroom.
The breach saw her suspended from work for six months after an internal investigation found she and "a small number" of staff broke Tier 2 rules.
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Now that she has returned to the office, Kay has opened up about the incident, admitting she hadn't broken the rules on purpose but was "appropriately sanctioned".
"I thought I was Covid-compliant. I wasn’t. I made a mistake," she told the Daily Mail. "I was an idiot and I let myself and my viewers down. I’m sorry for what I did and for any heartache I caused the loyal friends with me at the time."
She added: "I paid for my mistake; quite rightly. My viewers told me how frustrated they were with me and they were right to do so. With time, the mood music changed and my viewers wanted me back."
Kay was suspended from Sky News for six months
At the time, Kay apologised for her "error of judgment", writing in a statement on Twitter: "I want to apologise to you all for an error of judgement.
"On Saturday night I was enjoying my 60th birthday at a Covid compliant restaurant. I am embarrassed to say that later in the evening I inadvertently broke the rules.
"I had been waiting for a taxi at 11pm to get home. Desperate for the loo I briefly popped into another restaurant to spend a penny. I can only apologise."
Kay apologised on Twitter after the breach
Her statement divided fans on social media. While some were sympathetic to her situation and unsure why she was apologising, others expressed their disappointment that she had broken the rules.
"Having to use the toilet is not an error of judgement! No wrong done at all Kay," one follower told the star, while another added: "You are only human Kay."
But another was less forgiving: "All those people who have had to miss out on milestone celebrations… chucking stones and glass houses spring to mind… You are going to resign, I assume."
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