He has resigned over concerns about the possible invalidation of professional indemnity insurance for independent financial advisers caught up in the scandal - an issue the PIA claimed to have ironed out months ago.
Mr Brown, in his resignation letter, said he was "deeply troubled" about the PIA's attitude towards forcing members to disclose privileged documents which may invalidate personal indemnity cover.
The PIA, however, said it had taken extensive legal advice on this issue, which had concluded that its monitoring arrangements would not invalidate personal indemnity cover.
Separately, the PIA will today issue a progress report on the number of urgent pensions mis-selling cases that have been dealt with. The report is expected to show only a slight improvement on figures leaked last month.Reuse content