BTCV has taken 1,500 sq ft at unit 1 Lockside Office Park, located at Preston's docklands.
The volunteer conservation organisation has agreed a three-year lease with landlords Ercor for an undisclosed sum.
Mark Harrison, a surveyor at Robert Pinkus & Co, which acted on behalf of Ercor, said: "The docklands have always proved popular. It's an attractive location that combines the benefits of an striking outlook with close proximity to the city centre and good local amenities, easy motorway access and more often than not, designated parking; a requirement that is difficult to come by in the city centre."
BTCV, which has a head office in Doncaster, was set up in 1959 to oversee environmental conservation work on projects throughout the UK and across the world.