The London Ambulance Service was hit by technical problems during New Year's Eve night, causing delayed response times, according to reports.
Difficulties in the control room manifested when the computer system crashed and staff had to resort to using pen and paper to record incidents for five hours.
Ambulance crews were forced to use radio communications rather than web-based mapping systems that they ordinarily operate. New Year's Eve is one of the busiest nights of the year for paramedics, according to the BBC.
Deputy Director of Operations, Peter McKenna said: "Due to technical difficulties, our control room was logging emergency calls by pen and paper from 12.30am to 5.15am.
"Our control room staff are trained to operate in this way and continue to prioritise our response to patients with life-threatening conditions, using the same triage system as usual. We also have additional clinicians on duty to offer control room staff clinical advice if it is needed."
The problem has been now been fixed but Kevin Bate from the Operations team said: "We expect to continue to be busy throughout New Year's Day. Many Londoners will wake up feeling unwell after a heavy night.
"We would encourage them to consider using other healthcare services such as walk-in centres or calling NHS 111 for health advice to ensure our medics are free and able to respond to the patients in serious and life-threatening conditions."