Breast Cancer Campaign's 'wear it pink' fundraising initiative has raised £500,000, exceeding its £140,000 target by more than 250 per cent.
In a direct mailout to 47,000 companies, schools and universities, the campaign requested that people wear a pink item of clothing to work and donate £2.
The initiative took place on 31 October, at the end of Breast Cancer Awareness Month.
The research charity also emailed the message to supporters throughout October, asking them to forward it to friends.
The charity's website featured a map of the UK, which it partly coloured pink to show that 143,000 people had passed the message on.
Joanna Coral, the manager who helped create the scheme, put the event's success down to its simplicity.
"Not everyone is allowed dress-down days. Think of barristers wearing jeans in court, for instance. Such professionals could discreetly wear pink ties or socks without it being intrusive."