Cleansing Databases for your own use and on behalf of others

Passing on a large Customer Database 'substantially all'

NationEnergy Ltd has a large Customer Database containing 20m customer records that are regularly cleansed against the PAF. They pass this data to a business partner who performs mailing and marketing activity on their behalf and wants to know whether the "substantially all" clauses of PAF apply.

Does Nation Energy Ltd need to be an End User?