It has rewritten the code to include a clear requirement for agencies to disclose their clients and consultants. There was previously no such requirement - even though disclosure is a condition of APPC membership.
The body was forced to act after it emerged that some firms have been telling potential clients that they adhere to the code, despite refusing to join the APPC.
Association chair Gill Morris said: ‘This is an important development for the APPC and will promote greater transparency and clarity in the PA sector.'
She added: ‘You can't say you quite like the sound of the code if you aren't actually signed up to it. This will make it a lot harder for those people who are saying that they adhere to the code when they are not actually a member of the APPC.'
It is understood that Labour backbencher John Grogan played a key role in forcing the changes. APPC sources said Grogan, who is preparing to publish an Early Day Motion on lobbying (PRWeek, 23 February), raised the alarm after he discovered non-member firms telling potential clients that they adhere to the code, even though they would not disclose their client list.
The move follows recent tenders that have asked for adherence to the code, rather than membership of the APPC. For example, Connect Public Affairs faced competition from Bell Pottinger Public Affairs for its account with the Thames Gateway London Partnership.
BPPA is not a member of the APPC, but it was invited to pitch on the grounds that it adhered to the general principles set out in the code.
The changes will not come into force until May.
Meanwhile, two more agencies have joined the APPC, taking the number of members to 42. The new additions are B2L Public Affairs and Positif Politics.