The facilities at Londonderry were inconvenient .
The facilities at Londonderry rapidly became inadequate to cope with the buildup in naval activity ; in late 1941 the Royal Navy started work on an additional base with extensive jetties at Lisahally about four miles ( 6 km ) from Londonderry .
The facilities at Londonderry were inconvenient and rapidly became inadequate to cope with the buildup in naval activity ; in late 1941 the Royal Navy started work on an additional base with extensive jetties at Lisahally about four miles ( 6 km ) from Londonderry .