New figures show that the number of young Cambridgeshire children taught in large classes of 31 or more has quadrupled since 2010.
In January 2010 there were 249 children in a class larger than 30 but by January 2015 this had soared to 1,377 – a massive 453% increase.
Daniel Zeichner MP said: “The Tories promised in their manifesto that they would ensure that there is a good primary school place available for every child.
"The reality is that their failure to properly handle the growing pressure on school places has meant every year more and more young children are crammed into expanding classes, threatening the quality of education they receive. At the same time, as I know from my postbag, parents are finding it harder and harder to get a place for their child at a local school.
"Employers also tell me that the lack of school places is stopping them from recruiting key staff. These short-term Conservative cuts are damaging local businesses.
“Rather than spend hundreds of millions on Free Schools in areas where there are already enough school places, this Government should be prioritising spending on areas where there are shortages.”