The trio – WellChild, Envision and Street League – join The Ergonomics Society, Music in Hospitals, and The Cancer Resource Centre on the media support body's six-strong list.
The competition concludes on 2 February, when three of the charities will receive pro bono PR support from Weber Shandwick.
The shortlisted charities were due to present an idea for a campaign to a three-strong panel on 25 January, with the winners entitled to 14 days of support from WS over a six-month period.
The prize has changed since last year after Media Trust decided it would have more value if WS was given specific campaigns on which to focus rather than just provide general advice.
The competition concludes on 2 February, when three of the charities will receive pro bono PR support from Weber Shandwick.
The shortlisted charities were due to present an idea for a campaign to a three-strong panel on 25 January, with the winners entitled to 14 days of support from WS over a six-month period.
The prize has changed since last year after Media Trust decided it would have more value if WS was given specific campaigns on which to focus rather than just provide general advice.