DTZ has won the retainer to market the massive leisure development opportunity at Derwent Forest in West Cumbria to potential developers.
Allerdale council and Cumbria County Council, which jointly own the land at Broughton Moor, said DTZ had beaten 'stiff competition from several other firms'.
The councils' statement said: "The news means that work can now get underway to promote the land – one of the largest brownfield sites in the UK – as an area for a prestigious leisure and commercial development."
The former armaments depot between Cockermouth and Maryport was bought from the Ministry of Defence by the councils in August 2008 after years of negotiations.
The acquisition and ongoing maintenance, marketing and site preparation are funded by the North West Development Agency.