By 1914 this train was running throughout the year, and outside the summer season carried through coaches to Padstow, Bude, Plymouth and Ilfracombe,[1][page needed] a presage of things to come.

However World War I reduced both the scope for holidays and stretched the railway's resources, and after this the L&SWR did not pursue a policy of having a premier named train on the route.

[3][page needed] The name was chosen as the result of a competition run in the staff magazine and the winning entry was submitted by Mr F. Rowland, a guard from Woking who won a prize of three guineas for suggesting Atlantic Coast Express.

At the junction, the Bude carriages were detached and the Padstow section turned south to Launceston, skirting the edge of Bodmin Moor before reaching Camelford.

On Summer Saturdays, the ACE consisted of up to five trains departing from Waterloo in the 40 minutes before 11:00, stretching resources on the long single-track branch lines to the limit.

Significant delays were frequent at the junctions, as coaches were detached or attached and shunted between the various sections of the train, belying the name of "Express".

The company's locomotive design department, under its innovative Chief Mechanical Engineer, Oliver Bulleid, had been working during the war years; Bulleid's two new designs of express locomotive, the Merchant Navy class Pacifics for services between Waterloo and Exeter Central and the lighter West Country and Battle of Britain class for the branches beyond, enabled improvements in timekeeping and reliability and facilitated the introduction of heavier trains.

Gradual improvements in schedules continued until the final acceleration in autumn of 1961, when the journey time from Waterloo to Exeter Central came down to 2 hours 56 minutes.

In 2008 First Great Western revived the name for a new summer only daily service from London Paddington to Newquay operated by High Speed Trains.

The bus had to make a diversion around the back streets of Holsworthy to avoid a low bridge – one of the surviving overbridges of the old railway route.