Kennedys is to merge with Scottish law firm Simpson & Marwick later this year after partners at both firms voted in favour of the tie-up.

The combined firm will be known as Kennedys, although Simpson & Marwick will be known as Kennedys Simpson & Marwick in Scotland for a period after the merger goes live on 1 November.

The news follows the firm's recent union with specialist aviation and aerospace law firm, Gates and Partners, in June.

Like Kennedys, Simpson & Marwick specialises in insurance and claims sectors. Simpson & Marwick also has a strong residential property practice in Scotland, with this group continuing indefinitely to trade under the name Simpson & Marwick.

The merger will take the combined number of partners to 220 and the total number of staff to over 1,500 worldwide. Combined projected turnover is expected to exceed £160m in the current financial year.

Kennedys broke through the £100m revenue mark for the first time last year, with financial results for 2011-12 showing a 12.7% turnover increase to £109.1m. The firm recorded a 9% rise in revenue for the 2012-13 financial year, reaching £117m.

Kennedys senior partner Nick Thomas said: "Like us, Simpson & Marwick has significant strength in the insurance industry and we both have extensive similarities in our client base. There have been a number of clients for whom, and cases on which, Kennedys and Simpson & Marwick have worked together over a number of years and it became obvious that a merger would benefit both firms' clients, partners and staff."

Peter Anderson, managing partner of Simpson & Marwick commented: "This merger is intended to continue the hard work and success we have achieved as separate firms to date. It is a natural progression from the firms' collaboration over a number of years. The end result will be a powerhouse dispute resolution and litigation firm with a complete UK-wide and Ireland offering and a major international presence. We are looking forward to working together to add yet further value to what we do for all our clients."

Kennedys has expanded significantly in recent years, merging with its Dublin associate office O'Hare O'Connor Walshe in June 2011, in the same month that it launched a presence in Brazil through an association with local firm Torres Marcellino & Associados.