University Hospitals of North Midlands NHS Trust (UHNM) and University Hospital Southampton (UHS) have critical incidents still in place, although measures have been stood down at Norfolk and Norwich University Hospitals (NNUH) and Portsmouth Hospitals University NHS Trust.

Katy Thorpe, chief operating officer at UHNM, said: ‘A number of our MRI scanners and theatres are unable to operate at normal capacity in the heat and humidity, which means some outpatient appointments are being postponed and rescheduled to allow us to prioritise urgent and emergency patients.'

Thorpe said pathology services had also been disrupted with appointments being rearranged at alternative locations.

UHS declared a critical incident on Thursday after extreme heat affected systems and critical clinical services, including theatres and diagnostic imaging, leading to cancellation of a number of planned operations and outpatient appointments.

Ambulance services

Ambulance services have also come under severe pressure with East Midlands Ambulance Service NHS Trust declaring a critical incident on Saturday.

London Ambulance Service stood down its critical incident after answering the highest number of 999 calls in its history on Friday as the capital continued to endure extreme heat.

Call handlers took 8,869 emergency calls during the day. Between 6pm and midnight they answered more than 500 calls an hour.

The service also responded to 688 Category 1 emergencies – another record for a single day.

Demand was higher than during May's heatwave and the peak of the Covid pandemic.