More blood donors are needed in Shepherds Bush - where one of London's busiest donor centres is based.
It's national blood week from 10-16 June, and there are still plenty of vacant slots at the local centre on the first floor of Westfield shopping centre in White City, between M&S and The Village.
If you're able to donate, register online at the Give Blood website or call 0300 123 23 23 to make an appointment.
"By giving an hour of your time, you could save up to three lives," said NHS blood and transplant director Paul O'Brien.
Stocks of blood in the NHS usually dip during the summer holidays. All types are needed, but there is always a need for donors with O negative blood type, used for patients receiving emergency transfusions.
Donors of Black heritage are particularly welcome as they are more likely to have Ro blood, the type needed to treat people with sickle cell, the fastest growing genetic blood disorder in the UK. Only two per cent of donors have Ro type blood, which is 10 times more common in black people than in white people.
Donated blood is also used to treat patients with cancer, blood disorders and those suffering medical trauma or undergoing surgery.
The Westfield blood donor centre is one of the few in the country where younger donors outnumber older counterparts, with two in three donors aged between 17 and 44.
