Professional indemnity insurance for private landlords

Hello all. Does anyone have any knowledge re professional indemnity to cover private landlords? This appears to be distinct from public liability and/or legal expenses cover provided with other policies, and would cover admin/contract/ deposit management etc errors if pursued by tenants and their no win/no fee solicitors. we were targeted by a tenant and his solicitor father last year for one unintentional mistake over a long term and successful series of tenancies, where no loss was suffered by the tenant, but we still had to settle for several thousand pounds. Had this been done by a letting agent, they would have been covered but as private landlords, we are not. Any contacts gratefully received. Thanks