The Caldicott Guardian role has no statutory basis. It was originally conceived as an advisory role, and to an extent it still is, though Guardians are accountable for any advice given. In practice, many information sharing and disclosure scenarios are decided by the Caldicott Guardian and it is important that these are documented.
Where the Caldicott Guardian is an executive director within the organisation, she or he will most likely already be accountable directly to the Chief Executive. Where this is not the case or the individual is not a member of the Board or senior management team, direct accountability to the Chief Executive may still be the most appropriate option, although accountability to a senior executive may be appropriate in some organisations. Accountability to the SIRO is not recommended, on the grounds that the SIRO might then overrule the Caldicott Guardian. They should have a relationship of mutual respect and ideally they should be of equal seniority. However, it is the good relationship that matters more than the detail of who does what.