Brown Lloyd James-financial has been set up following what the agencies described as 'successful co-operation on a number of shared client accounts'.
Under the deal financial PR will be provided to BLJ's existing and new clients. mj2 will continue to serve existing clients and source new clients under its own brand.
In a linked move, BLJ founder Sir Nicholas Lloyd, former editor of the Sunday People, the News of the World and the Daily Express, has joined the mj2 board as a non-executive director.
According to mj2 managing director Christopher Joll, the idea of the alliance emerged when he and BLJ co-founder Howell James, formerly head of John Major's political office, talked about BLJ being unable to carry out some financial and industrial work due to staff limitations.
A joint venture under a single brand was formed to enable mj2 - set up by Joll with colleagues Tim McCall and John Evans in February - to take on some of the work.
It was also considered the answer on how to pitch for new business as two agencies 'without over-complicating the process'.