The long-promised direct trains from London to Amsterdam will start in December this year — but a regular service may not run until Easter.

Direct trains from London to Amsterdam have long been promised. German Railways even went so far as to run a train to London St Pancras and announce a 2013 start date. But that deadline came and went, and the German firm has not shown any indication lately of taking on Eurostar.

Eurostar maintains that it will launch a service from St Pancras to the Dutch capital in December this year — but makes no promises about running regular services until the following Easter.

Last year Eurostar’s chief executive, Nicolas Petrovic, said: “Over the coming months, we are making a major investment in our fleet, our service and our stations to equip our business for expansion. The launch of our Amsterdam route at the end of next year marks a key milestone and represents a significant growth opportunity for the future.” Many prospective passengers inferred that daily services would commence in December 2017 and continue indefinitely.

But according to Railnews magazine, it appears that may not be what Eurostar has in mind.

The magazine quotes a “company source” as saying: “We do not expect to run regular services to the Netherlands until Easter 2018, to coincide with the beginning of the City Break season.”

The trains will run via Brussels to Amsterdam, calling at Rotterdam. It is expected that the outbound journey will take 3 hours, 50 minutes, slicing nearly an hour from the existing service involving a change of trains in the Belgian capital.

Coming back, there is a protracted stop in Brussels, where other passengers will join the train, adding around 20 minutes to the journey.

On an average weekday there are 42 flights each way between the London airports and Amsterdam, including 15 from Heathrow, 11 from London City and 10 from Gatwick. The typical journey time is 75 minutes.

But Mark Smith, founder of the Seat Sixty-One international rail website, expressed optimism about the international train’s prospects: “This is a route where high-speed rail can make real inroads into a market that airlines think is their own.