The two agencies will retain their independence but will co-operate on a range of services to provide a 'one-stop-shop' facility, with the offer of public affairs, financial and corporate PR and crisis comms.
Hanover, with offices in London and Brussels, was founded in 1999 by former Conservative Central Office director of comms Charles Lewington. The agency specialises in public affairs, corporate comms and financial services.
Powerscourt, with offices in London and Dublin, was founded in 2004 by former Goldman Sachs director of corporate affairs Rory Godson. It offers financial and corporate PR, as well as crisis comms.
Between them, both agencies have 100 employees, combined revenues of £15m in 2014 and are owned by their managements.
Hanover managing director Lewington said: "An increasing number of our clients are seeking financial PR. We look forward to working with the expert team at Powerscourt to deliver deep expertise that helps our clients achieve their business objectives. We hope that this will lead to a developing relationship between our firms."
Powerscourt chief executive Godson added: "In a time of political flux and with the increasing importance of regulation, clients see a continuum between public affairs and financial PR. We are linking with Hanover to offer depth and quality. We have already worked together on a number of projects and have no doubt that this will be a successful partnership for both agencies, and our clients. We look forward to an evolving relationship."