Dean Hill had been in use as a munitions storage facility since the 1940s and had facilities for the underground storage of an extraordinary amount of munitions, including a bunker to hold nuclear warheads; Surplus to Ministry of Defence requirements, the site was decommissioned in 2003 and put out to tender in November 2005.
Dean Hill closed in 2003 and by 2004 D6660 was briefly in the ownership of Roger Craven of Essex before being sold to the L&B in August 2005. Following a major overhaul including regauging, it entered service as Heddon Hall at the end of 2005.
During Autumn 2007 the loco was given a full engine overhaul and the exhaust was modified to vent through a bonnet-mounted pipe.