Clyde & Co has sealed a merger with Scottish firm Simpson & Marwick in a deal which will go live on 1 October.

Simpson & Marwick has eight offices, with five in Scotland and three English bases in London, Leeds and Newcastle. The merger will hand Clydes, which has 37 bases around the world, its first presence in Scotland.

Simpson & Marwicks revenue for 2014-15 was £28.5m; the merger will take Clydes total revenue to over £420m.

The Scots firm, which has 45 partners, is particularly well-known for its insurance disputes practice. The firms announced in May that they were in "advanced discussions." In the same month a three-partner family law team left Simpson & Marwick to join Brodies.

Clydes senior partner James Burns said: "From our perspective the driver is to complete a UK national service for our clients in a number of different sectors. Simpson & Marwick is the pre-eminent Scottish insurance firm."

Simpson & Marwick managing partner Gordon Keyden said: "It's a tailor-made fit – similar practices, similar clients, two good robust firms with a clear shared strategic view of what the insurance market in the UK needs."

The combined firm will be known as Clyde & Co, but Keyden added that Simpson's residential property practice will continue to trade under the Simpson & Marwick name due to the strength of the brand.

Simpson previously held merger talks with Kennedys in 2013 which fell through. Kennedys opened offices in Edinburgh and Glasgow in January of this year.

The merger marks the latest in a number of tie-ups which have transformed the Scottish legal market in recent years. In 2012 McGrigors merged with Pinsent Masons, while the same year also saw the combination of Burness and Paull & Williamsons to form one of the country's biggest law firms. Former 'big four' Scots firm Dundas & Wilson was subsequently taken over by CMS in 2014.