A regular visitor to Holyhead throughout her career for annual overhaul and dry docking, it was not until her final weeks in Sealink service that the Vortigern would see service on the Dun Laoghaire route.
Built in 1969 as a multi-purpose passenger and roll-on roll-off ferry for cars, lorries and trains, the Vortigern was unique in being British Rail's first Dover vessel to be diesel-driven and also to be equipped with a bow visor and variable-pitch propellers. Delivered to her new owners on 18 July 1969, and arriving at Dover ten days later she replaced the turbine steamer Dover which then transferred to Holyhead. On 31 July the Vortigern commenced regular summer service, with the 16.00 sailing to Boulogne. Being able to function either as a conventional train ferry between Dover and Dunkirk, or as a car ferry to and from Boulogne, made her a most flexible unit, generally seeing use as a train ferry in the winter months. One main deck held road and rail vehicles and two auxiliary decks carried cars. Her inaugural run to Dunkirk as a train ferry was on 18 September 18 1969.
In 1978 the Vortigern's annual overhaul at Middlesbrough included the £200,000 conversion of her after boat deck garage (in use when the ship operated as a train ferry) to a passenger lounge, raising her passenger certificate from 1,000 to 1,350. This reflected her more usual passenger-car ferry role. Other, minor changes took place - the main one probably being the modification of her hull belting to allow a better fit at Folkestone.
The following year saw the Vortigern arrive for dry docking at Holyhead on 29 October 1979, entering the dock on 6 November once if was vacated by the Avalon. It was on this occasion that she almost saw service to Dun Laoghaire, local management at the Welsh port being anxious to use her in place of the failed St Columba. However Dover protested and the spare Maid of Kent was called in from Weymouth.
The beginning of 1981 marked the start of a troublesome two years for the Vortigern. On 16 January she suffered an engine room fire, resulting in much damage to her electrical installation and four weeks as Wallsend undergoing repairs.
Then in June she grounded while going astern out of Boulogne. However it was on 4 March 1982 that the Vortigern suffered her darkest hour, running aground on a stone groyne 21 degrees 2.2 cables from Ostend West Pier light, whilst operating the 00.10 Folkestone - Ostend service. It was not until 6 March that she cleared the obstruction with the aid of tugs and was able to proceed into Ostend (No.3) for discharge of vehicles. She then moved on to a lay-by berth (deep water quay) to await entry into the floating Dry Dock for inspection. She subsequently sailed to Amsterdam for repairs, not resuming service at Folkestone until 23 April. Again she blotted her copy book, striking the pier at Folkestone, damaging her Port Quarter, while operating 20.10 Calais - Folkestone service on 3 July 1982. She was dispatched to Zeiglen Yard at Dunkirk Dry Dock 4 July, returning to service after repair on 10 July.
The Vortigern's final years under the red ensign were not happy ones. Under the ownership of Sea Containers' Sealink British Ferries she was arrested by the Admiralty Marshall on behalf of the National Union of Seamen on 12 November 1986 over unpaid redundancy cheques for crews at at Portsmouth. She was released the following day when the cheques were promptly issued. The ship was scheduled to finish service on the Dover Straits four days later and it was expected that she would be transferred to Weymouth, however she remained at Folkestone to cover winter refits of the Hengist and Horsa.
In January 1987 she was called upon to operate the Fishguard - Rosslare route while the St Brendan was on overhaul.
Following the Herald of Free Enterprise tragedy off Zeebrugge in March 1987, Townsend Thoresen chartered the Vortigern for £250,000 over a period of 60 days for use on their Dover-Boulogne link. It was a period fraught with difficulty, the ship making newspaper headlines due to the poor standard of her tired accommodation. Over the Easter period she missed a number of sailings following a small electrical fire. On completion of the charter in June she sailed for layup at Falmouth, her first idle summer.
She was reactivated on 6 August to operated the Newhaven - Dieppe service for the broken down Versailles and between October 1987 and January 1988 she was back in service between Folkestone and Boulogne replacing the Hengist, which had grounded during the great storm that caused much devastation in the south east of England. Her final days at Folkestone were marked by technical problems. First, she suffered a bow door defect, continuing in service as a stern loader until the fault was rectified. Then on 31 January 1988 she suffered a bow thrust fault and was unable to enter Folkestone in a SW gale. She diverted to Dover where it is thought she was the first ferry to use the new Number One linkspan on the Eastern Arm.
The Vortigern's Sealink story ends at Holyhead. Having been laid up at Chatham in Kent pending disposal she was reactivated by Capt Trevor Shaw and his crew for operation on the Dun Laoghaire freight service on 7 march 1988 following an engine failure in the Stena Sailer. Arriving at Holyhead two days later the ship made her first crossing to Dun Laoghaire on 10 March.
The Vortigern was deprived of the opportunity to operate on the passenger service and after the 0215 sailing to Dun Laoghaire on 31 March she returned to Holyhead in ballast under the command of Capt Tudor Jones. There she was handed over to her new Greek owners, Lindos Line and renamed Milos Express.
Entering service after a major and much needed refit in time for the summer season, the Milos Express commenced service between Piraeus - Kynthnos - Serifos - Sifnos - Milos, and sometimes also between Sikinos - Kimolos - Folegrandros.
On 12 November 1999 Lindos Line was purchased by Minoan Flying Dolphins and in January 2000 her name was changed to Express Milos for operations with Hellas Ferries.
A further sale came in May 2003, becoming Saos Ferries' Nisos Limnos serving the Dodecanese Islands, including Samothrace.
In September 2004 she was sold to Indian breakers for scrapping and three months later, renamed Limon she sailed for India. She was reported arriving at Alang anchorage for scrapping on 13 January 2005.