I am an Accredited Mediator in the sense I've passed the accredited mediation course offered by CEDR. [Institute of Chartered Accountants England & Wales] Unfortunately the CEDR website does not maintain a list of 'its qualified mediators'. As CEDR does not regard itself as a regulated professional membership body it does not offer letters of good standing. Web-based proof of qualification and membership, ongoing or otherwise, is therefore not available.
