BDO and PKF have formally completed their merger and from today will be operating as one firm, under the BDO brand and as part of BDO's international network.

The combined firm has revenues of nearly £400m and employs 3,500 people across 24 UK locations, including 300 partners. It also belongs to the largest global accountancy organisation aimed at the mid-market, which has revenues of over $6bn (£4bn) and operates in 138 countries worldwide.

Simon Michaels, managing partner of BDO, said the merger had created 'one of the strongest firms focused on the mid-market, with the breadth and depth to work with ambitious businesses that want exceptional service and access to impressive UK and worldwide networks. We've got talented people, an ambition to grow from this position of strength and firm financial foundations'.

'The merger has transformed our national market presence overnight, but the hard work starts now. Everyone is now focused on building on our ambitions still further and responding quickly to the domestic and international environment. We also remain focused on delivering exceptional service to our clients and creating the right environment for our people to develop and grow,' Michaels said.

The merged firm will have a combined turnover of of nearly £400m, which will push them up the rankings to number six spot, slightly behind nearest rival Grant Thornton, which reported June 2012 year-end revenues of £417m.