Rail passengers from Huntingdon and St Neots can expect two more trains to London in the morning rush hour - together with hundreds more seats - when a major shake-up of Govia Thameslink Railways services takes place.
GTR, which runs Great Northern, described the changes as the "biggest ever" in a key advance for rail expansion.
The new schedule will come into effect on May 20.
Great Northern will run more and longer trains from Huntingdon and St Neots to London in the morning peak, increasing from 10 to 12, six going in to Kings Cross and the other six to St Pancras, a new destination, and on through central London to Farringdon, City Thameslink, Blackfriars and London Bridge.
One of the trains, the 5.54am from Peterborough, calling at Huntingdon at 6.11am and St Neots at 6.18am, will not run in the first three weeks of the transition period.
In the evening peak return journey there will be longer trains, although the number running will remain at 11, nine of which will operate in the first week of the new timetable and then 10 in the second week. The two services affected are the 4.16pm and the 6.46pm, both from St Pancras.
Five of the trains will leave from Kings Cross and six from St Pancras.
A Great Northern spokesman said year-on-year there would be 30 per cent more carriages and 20 per cent more seats - almost 1,300 extra - and 80 per cent more capacity in the morning from the two local stations after a three-week transition and 25 per cent more carriages and 20 per cent more seats - 1,200 extra - in the evening after a two-week transition phase.
Charles Horton, GTR chief executive, said: "A huge number of passengers will notice the benefits in terms of new journeys, better intervals between trains, improved reliability, and more capacity across a wide region.
"We are redeploying trains and crew and there may be some disruption, so we ask passengers for their understanding during the transition period of several weeks during which time a very small number of trains will not run.
"Almost a quarter of all rail journeys are taken on the GTR network and because of the necessary scale of the change we strongly urge passengers to check ahead as to how their journeys will be affected."
There will also be direct Thameslink services from Peterborough to Horsham via London Bridge and Gatwick airport.