The Met Police has closed its last investigation into alleged Covid breaches in Parliament, the force said on Friday.
Detectives said no further action will be taken against Conservative MPs and Lords regarding a gathering on December 8, 2020, the final pandemic party in Westminster police had been looking into.
The party was said to have been arranged by Commons Deputy Speaker Dame Eleanor Laing to celebrate the birthdays of Tory MP Virginia Crosbie and peer Baroness Jenkin, whose husband Sir Bernard Jenkin was a member of the privileges committee that found Boris Johnson had lied to Parliament.
The event was said to have happened when London was in Tier 2 measures that restricted indoor socialising.
When police first began looking into potential breaches at the party in July, former Prime Minister Mr Johnson accused Tory MP Sir Bernard of "monstrous hypocrisy" for allegedly attending the event before sitting on the cross-party panel which found the had lied to MPs with his partygate denials.
However it was announced on Friday that Sir Bernard is still being investigated by Parliament's Standards Commissioner over the alleged birthday bash.
The Met said officers "assessed the available information and concluded it did not meet the threshold" for any fines and that there would be no further action.
It had already been confirmed by a spokesman for the Commons Speaker's Office that Dame Eleanor did not receive a fixed penalty notice from police regarding that event.
Ms Crosbie had also said she did not get a fine.
It brings to an end the force's investigations into alleged breaches of Covid regulations, which previously led to fixed penalty notices for Mr Johnson and then-chancellor Rishi Sunak over a gathering for the former prime minister's 56th birthday.
More than 100 fines were issued to MPs and staff across Whitehall and Downing Street for breaking lockdown restrictions in a scandal that led to Mr Johnson's downfall as PM.
The Covid inquiry heard this week that Mr Johnson said the Government must “smash on” and would “come out on top” in messages to his Cabinet Secretary as revelations of pandemic partying in Downing Street emerged.
In a statement, the Met said: "Our approach to the assessment of these allegations has been consistent throughout. The individuals affected have been told there will be no further action.
"This now concludes all assessments or investigations by the Met into alleged breaches of Covid regulations."
