According to the poll, Labour support has risen one point to 40 percent, the Conservatives have dropped two to 33 percent and the Lib Dems are up one to 11 percent.
Senior Tories had hoped that the Partygate problems were now behind them and voters had moved on.
However, Michela Morizzo, Chief Executive of Techne UK, said when reminded of the poor behaviour in Downing Street during the Covid lockdown, voters tend to react angrily.
She said: “The gap between the parties in our tracker has not been this big since 11 February, before Russia’s invasion of Ukraine began. While many voters will not have been surprised by this week’s report by Sue Gray, it has reminded everyone of what went on in Downing Street.”
“The Prime Minister may hope this draws a line under ‘Partygate’, but every time voters are reminded of what happened, support for the Conservatives drops. It continues to be an open wound for Boris Johnson and there is no sign that will heal anytime soon.”
The report also appeared to have dented confidence in the Government – which was down two points to 31 percent – while those who expressed a lack of confidence were up two percent to 64 percent.
Most Conservative MPs have continued to back the Prime Minister this week after Ms Gray said it was time to “move on from the scandal.”
However, Brexiteers John Baron and David Simmonds came out this week to call for him to go taking the number of Tory MPs publicly opposed to the Prime Minister staying to 19.
However, one loyalist has dismissed them as “the usual suspects of the disaffected and Remainers.”
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Worryingly for Mr Johnson, one in 10 who voted Conservatives in 2019 said they would be highly unlikely to vote, the biggest amongst all the parties.
Conservatives are behind Labour in every age group apart from pensioners (65 and over) where they hold a lead 45 percent to Labour’s 31 percent.
The polling came before Rishi Sunak’s announcement on helping with the cost of living where pensioners received more help.