Budget Group is set to jump up the brokers' league table after its affinity business, Junction, won an administration contract worth £317m from the National Australia Bank Group.
The deal will bring in an extra £6m a year brokerage.
This will help push Budget Group's annual total to an expected £75m-£80m putting it close to Hill House Hammond (HHH).
HHH is 12th in the 2002 Insurance Times Top 50 Brokers table with a brokerage of £82m.
Budget is currently 20th, based on figures excluding its subsidiary Dial Direct.
If these are added in, the group is close to Swinton which lies at 15th on £60.8m.
Under the contract, Junction will provide access to home and motor cover and third party services for Clydesdale Bank, Yorkshire Bank and Northern Bank, which are all customers of NABG's subsidiary National Australia Insurance Services, the 14th largest broker.
Budget Group chief executive Peter Winslow said the deal was important not just because of its impact on the bottom line, but as an endorsement of company quality. "It is a very rigorous organisation and is tremendously thorough in selecting the partner it wants."
Together the three UK banks have nearly 2.8 million customers.
Junction will take on a policy base of 101,000 home insurance customers and 36,000 motor insurance customers.
The work will initially be done from a call centre in Peterborough before moving to a new centre in Sunderland, where it will create up to 400 new jobs over the next five years.