The combined fee income of £30.9m will push the merged firm into 22nd place in the annual Accountancy Top 75 accounting firms in the UK, Currently ranked at number 28, Kreston Reeves reported fee income of £21.9m in 2015, and Spofforths, ranked at 62, had a fee income of £9m for the year.

The two firms will announce further details of the merger and the structure of its management team in late May 2016. Bringing the two firms together will create a partnership with 45 partners and directors, and over 450 staff.

Kreston Reeves has 39 partners and 300 staff, with offices in London, Canterbury, Chatham, Discovery Park (Sandwich), Eastbourne and Gatwick (Crawley).

Spofforths has 16 partners and directors supported by 165 staff. Its offices are located in Brighton, Chichester, Horsham and Worthing.

There will be a transitional period during which Spofforths will embrace the Kreston Reeves brand while the two firms integrate people, processes and systems. On completion of the merger, the firm will operate as Kreston Reeves LLP.

Nigel Fright, managing partner of Kreston Reeves, said: ‘We are delighted by the prospect of this merger, which reflects our mutual ambition to expand in the south east. Spofforths is a successful firm that shares our values and strong personal commitment to clients.

'The result will be a fuller, more innovative, more integrated accounting, business advisory and financial planning service, delivered by 55 partners and more than 450  staff, spread across 10 locations in the south east.’

The merger should also increase opportunities to pitch for international business, particularly through the Kreston international network.

Richard Spofforth, managing partner of Spofforths, said: ‘The merger is being undertaken by both firms from a position of strength, with each bringing skills and experience to the other. It's going to be an exciting time for all of us: it's a joint step forward and together we're going to build a firm for the future that responds to all the changes around us.’