A stitch can save lives – that is the hope of a new NHS campaign launched in Dartford this week.

The NHS Blood and Transplant team (NHSBT) is reminding people that ‘blood does not grow on trees’ and that new donors are needed, as part of its new ‘yarn bomb’ campaign.

Yarn bombing is a type of graffiti or street art that employs colourful displays of knitted or crocheted yarn rather than paint or chalk.

Soon people will be waking up to find woolly street art adorning trees in city centres and outside railway stations in a bid to make them think about donating blood.

Rebecca Willis, a Year 13 student from Dartford Grammar School for Girls, was involved in developing the knitting pattern for the blood drops being placed in trees.

The campaign was launched at her school this week.

A spokesman for the school said: “We have yarn bombed a tree with red knitted blood drops to create a visual representation that there is not an endless supply of blood and they need more donors to sign up.”

A spokesman from NHSBT added: “We need around 200,000 new donors each year just to keep our numbers stable.”