Putsmans and Shakespeares are to join forces in a move which puts the new law firm into the top ten list of legal s ervice providers in Birmingham.
The merger will create a business with more than 300 staff, 50 partners and a turnover of approximately £20 million.
According to figures published in industry directory Legal 500 last month, it will be placed in the top 80 law firms in the UK and rank at around number five in Birmingham in terms of the number of fee earners.
It will come into being next April and plans are already underway to begin the integration.
Staff will move onto a single site on Temple Street currently occupied by Shakespeares. It has the space to accommodate both sets of employees while Putsman's lease on its Great Charles Street building is nearing an end.
"The combined forces of the new firm will offer a comprehensive range of legal services to businesses and private individuals as well forming an impressive insurance and personal injury division," the pair said in a statement.
Paul Wilson of Putsmans will be the firm's chief executive with key roles also filled by Putsmans chairman Terry Lipscombe and Mike Hibbs, senior partner at Shakespeares.
Exactly what is yet to be agreed - from top to bottom posts will be decided on the best person for the job rather than one-for-one trade offs, all insist.
Some jobs may go as part of the integration although they are not for now being quantified. It is hoped to achieve it through natural wastage.
"Conversely there is a determination "to grow lawyer numbers aggressively".
Mr Wilson said: "This merger between two of the city's oldest firms will create a new force in the legal market.
"This means that our combined client base, which already includes some impressive national brand names, and our extensive pool of legal expertise will provide a strong platform from which to grow our business.
"We will continue to offer high quality legal services to small and medium-sized businesses, smaller plcs and high net worth individuals as well as advising the number of high street banks for which we currently act."
It puts the new firm roughly around the size of Martineau Johnson.
Wragge is out in front as the top Birmingham firm with turnover over £100 million and more than 1,000 employees.
Shakespeares and Putsmans said they recognised the need to get bigger in order to compete for talent and clients.
They say cultures are similar and the intention is to drive six core areas - private client, corporate and commercial, employment, insurance, commercial property and commercial litigation.
A special team has been put in place to make the merger work - the two parties have been talking to each other on a deal for about three months.
Mr Hibbs said: "This announcement marks the start of a very exciting period for both firms as we prepare for the official launch in the Spring of next year. With Shakespeares' 150 years of history and Putsmans equally prestigious background we have the foundations in place to build a dynamic new firm which will make a huge impact on Birmingham's legal services market."
Mr Lipscombe said: "Our firms have built their reputations by offering excellent legal advice to our Midlands and national client base at a sensible price. We will continue to be partner-lead when delivering services to clients and to adopt a very personal and practical approach to helping our clients achieve their aims.
"Shakespeares and Putsmans have always had the potential to attract a range of good quality clients and our combined resources will create the impetus needed to further build on those strengths to create one of the UK's most successful law firms."