The original three LSTs were joined in 1948 by another vessel, , renamed "Empire Doric", after the ASN were able to convince commercial operators to support the new route between Preston and the Northern Ireland port of Larne. Originally Liverpool was chosen, but opposition from other operators led to a move to Lancashire. However, special port facilities had to be constructed at both Preston and Larne before the new route could be opened – a wartime end-loading ramp built by engineers during World War II at Preston, and a floating pontoon from a Mulberry harbour connected via a bridge to the quay at Larne.