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Trish Greenhalgh, 62, was devastated by a leaked Downing Street video showing Boris Johnson’s former spokeswoman Allegra Stratton joking about a rule-breaking Christmas party at No10 last year

A professor has slammed Downing Street staff for laughing about their rule-breaking Christmas party shortly after her mum died alone in hospital.

Trish Greenhalgh said her mother, Mary, was admitted to hospital on the day official Allegra Stratton joked about the bash in a practice press briefing last year.

Mary, 94, died from coronavirus on December 27 – just five days after Boris Johnson’s former spokeswoman answered mock questions about the drinks at No10.

The Government previously insisted no rules were broken, however Ms Stratton said there was ‘definitely no social distancing’ in the newly leaked video.

In a heartbreaking tweet, Trish, 62, said: “Dear Allegra Stratton, on the day you partied, my mother called me, breathless and feverish. I didn’t visit.

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“On the day you joked, she was admitted to hospital. I didn’t visit. As you celebrated Christmas, she died without family by her side. I promise you, it wasn’t funny.”

Prof Greenhalgh told The Mirror: “I was really devastated to see the video of Allegra Stratton joking about a party that appears to have taken place on the very day my mother became unwell with Covid.

“They seemed completely unaware of the deep significance of the sacrifices my family and many many others were making – not attending a loved one to provide comfort and say our final goodbyes.

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“Memories of a Christmas party usually fade quickly; memories of an emotionally painful death never fade.

“It was a difficult death because hardly anyone was vaccinated at that time, so visiting people in hospital carried a high risk of catching Covid and potentially transmitting it to others.

“To avoid that, none of the family visited my mother with the exception of my son who is a junior doctor and had had one jab.

“We weren’t allowed to visit her anyway until it was clear she was terminal – because of the hospital’s Covid rules.”

Prof Greenhalgh said her son was the only loved one to visit her mum in her final days in William Harvey Hospital in Kent.

She added that her family was ‘very reluctant’ to keep everyone else out – but in the end they decided it was the ‘safest option’.

Boris Johnson finally “apologised unreservedly” over the No10 Christmas party at Prime Minister’s Questions today – although he denied all responsibility, continued to claim he was told rules were followed, and threw his own staff under the bus.

Mr Johnson said he was “sickened and furious” at the clip of his staff laughing about a Christmas bash four days after it happened last December, when lockdown rules banned social gatherings.

After a week of stonewalling questions, and No10 claiming there was no party, the PM announced an investigation by the Cabinet Secretary and disciplinary action if the rules were broken.