DIBB Lupton Broomhead has come through a seven-month tendering process to win a one-year contract as employment law advisers to the Government's Employment Service.
The contract, which starts on 6 November, will involve the provision of policy advice on staff terms and conditions but the firm has also been signed to litigate on behalf of the service in industrial tribunal actions.
Head of employment David Bradley, who is based at Dibbs' Sheffield office, said it was impossible to predict the financial worth of the contract, but indicated it was "substantial".
"We decided to tender because we saw it as a huge opportunity for us," said Bradley. "They're a gilt-edged client. I don't think you could want to act for a more prestigious client than a government agency.
"It will be a very significant contract as far as work throughput is concerned. It will certainly be in the top five of our clients," he added.
Bradley said the firm's ability to provide national coverage to the service's 1,200 offices had played a key role in winning the contract. Dibbs competed with approximately 20 other firms on the initial shortlist, before joining a handful of them in a beauty parade.
"The feedback I've had from the Employment Service was that because we had so many dedicated lawyers and we were able to provide a national coverage they were convinced that we could offer a consistently high level of service across the country," said Bradley.
"When you're dealing with that number of sites and you're looking to provide a consistent and cost-efficient service you've got to be able to supply employment lawyers out of more than one office."
A spokeswoman for the service said Dibbs won the contract because it offered "a complete service covering all of our requirements".
"Against strong competition their tender offered value for money with national coverage from a team specialising in all aspects of employment law."