Across the UK, a group of volunteer motorcyclists is helping the NHS by delivering blood. What motivates them, asks Simon Fry.
Isabel Kydd is on call for 80 hours of one week each month. At very little notice, she can be woken in the night and find herself riding a motorbike with a vital delivery for a hospital.
But she's not an NHS employee. She's just a volunteer, one of 1,400 advanced qualified riders of the Nationwide Association of Blood Bikers (NABB).
In 2013, the association's bikers responded to around 35,000 rapid transport requests from 262 UK hospitals. They are almost a Deliveroo for the NHS.