The London Ambulance Service has been taken out of special measures after improving its rating from "inadequate" to "good".
The Care Quality Commission (CQC) on Wednesday released a report which rates the organisation as "good" overall and "outstanding" for patient care.
The report said that staff often went above and beyond their expected duties in order to meet patient needs.
Inspectors saw and heard about examples of the commitment of staff from patients, acknowledging that the Service was involved in treating those involved in major incidents in the capital last year, including the London Bridge and Westminster Bridge terrorist attacks.
In 2015, the CQC rated the Service "inadequate" for safety and leadership, while judging that the responsiveness and effectiveness "required improvement".
Now, all of those areas are rated "good".
Professor Ted Baker, England's chief inspector of hospitals, said: "The improvements the leadership and staff of London Ambulance Service have made are especially commendable - and especially necessary - given the major incidents the Trust has responded to over the past year, including terrorist attacks and the Grenfell Tower tragedy."
London Ambulance Service chief executive Garrett Emmerson, who joined the Trust in May last year, said: "I am delighted the dedication and hard work of staff throughout the Service has been recognised by the CQC.
"In particular, I want to thank staff for continuing to provide outstanding care.
"The CQC again gave London Ambulance Service the highest possible rating for the care we give to patients and I am extremely proud our incredible frontline staff have been recognised in this way."
London Mayor Sadiq Khan said: "I welcome today's announcement by the Care Quality Commission that London Ambulance Service has been rated good.
"This recognises the improvement in the service provided to Londoners by the Trust over recent months.
"My thanks go to all of the staff at the London Ambulance Service who made this possible and who work tirelessly for Londoners every day."
The London Ambulance Service is the busiest emergency ambulance service in the UK, receiving about 5,000 calls a day and responding to incidents across London in ambulances, response cars, bicycles, motorcycles and by helicopter.
The service has more than 5,200 staff working across its teams.
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