Rail passengers are angry that train operator Thameslink is once again running trains with fewer carriages.
Peak-time Thameslink trains are overcrowded again
Bedford Commuters' Association said enough passengers to fill around 11 carriages were getting on trains with only four, down from eight.
While Thameslink was unable to operate through-London during Channel Tunnel link work, it hired extra rolling stock to run north and south of the capital.
When work ended, those trains went back and it is short of rolling stock again.
The commuters' association said it received more complaints about overcrowding than anything else.
Thameslink's through-London train service began again on 16 May after eight months of disruption while work was carried out on the Channel Tunnel Rail Link and the new Thameslink station enclosure at St Pancras.
Thameslink said it had been unable to get hold of any more rolling stock but that when another company takes over the franchise in April 2006, it will have to provide eight carriages on all trains during peak times.
Thameslink, which has run the rail franchise since privatisation, is not included on the Strategic Rail Authority's list of five preferred bidders.