For the candidate’s own material, the promoter will usually be the agent. The person on whose behalf the material is being published will usually be the candidate.
An imprint on candidate campaign material should look like this:
Printed by [printer’s name and address].
Promoted by [agent’s name and address], on behalf of [candidate’s name and address].
Promoted by John Smith, on behalf of Jane Smith of 112 High Street, Airdrie, AD1 1AD.
Where the candidate is also the promoter of the material, the ‘on behalf of’ part of the imprint is not required. This may happen when a candidate is their own agent.